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How to Keep Your Oscar Fish Happy & Healthy

If you are intending on keeping Your Oscar fish healthy and disease-free then it is very important that you know a little bit about fish health. Keeping fish in an aquarium is a huge compromise compared to what their life would be like in their natural environment. The majority of fish we keep come from the tropics where their water is extremely clean. Because of the amount of water involved when keeping tropical fish in home aquariums, it is going to be absolutely impossible to emulate the cleanliness of their natural waters. A fish in its natural environment doesn't have to worry about ammonia, nitrite or nitrate because they have millions and millions of gallons of water at their disposal. At the very best, you would only have a few hundred gallons for your fish to live in, in most cases, less than 100 gallons, a small puddle in the Amazon.

Because home aquariums contain such little water, fish waste pollutes the water very quickly. Polluted water contains harmful organisms which can cause illness in fish. In the wild fish rarely come across harmful organisms, they are more capable of warding off infection. In your home aquarium, harmful organisms multiply very quickly, your fish will always be picking them up. However, if your fish is fed well, stress-free and you carry out regular tank maintenance, the fish can quite easily resist these harmful organisms.

Some of you may remember goldfish at fairs, I certainly do, seeing them in bags hanging up waiting for someone to win them. Thank god this doesn't happen much any more. Most of those goldfish won would have had a pretty miserable, and probably very short life due to the fact that most of the people didn't know the first thing about looking after a fish. They thought it would be perfectly okay to take it home, fill a bowl full of water and let the fish live in it. Unfortunately, this does still happen with fish such as Oscars. If you are going to keep Oscars, you really need to look after them properly and give them a first-class environment to live in, if you don't, you're going to have problems.


Toxic Talk

Fish produce ammonia
by excreting it through the gills, it is also contained in solid waste, and dead matter such as fish and plants. Ammonia is very toxic to fish and is often the cause of fish death and illness. Ammonia is removed from your water flowing through your biological filter, ie. often sponges and the stuff that resembles dog biscuits or macaroni inside your filter, referred to as media. Billions and billions of bacteria living on this media consume the ammonia contained in the water which in turn changes it into a slightly less toxic element called nitrite. Once again bacteria in your biological filter consume nitrite and the same process turns the nitrite into a very less toxic nitrate.

When you test for ammonia using your aquarium test kit, the reading you actually have is a combination of ammonium (NH4 + or ionized ammonia) and ammonia (NH3 or unionized ammonia) known as Total Ammonia Nitrogen (TAN). Ammonia is the toxic part of the Total Ammonia Nitrogen. Even at high concentrations, ammonium does not cause mortality in fish. The pH and temperature of your water will determine the toxicity of your water if your ammonia test results are high. For instance if your test results show that you have 5 ppm of ammonia (TAN) present then this is obviously not good. However your pH level will determine whether or not this is actually ammonium or ammonia. Remember that ammonia is the toxic part of Total Ammonia Nitrogen. So if your pH is 7.0 and your water temperature is 28°C then you actually only have 0.3 of ammonia present in the water. On the other hand if your pH is 9.0 and your ammonia is 5 ppm at the same temperature than the ammonia present in the water is actually 2.0, extremely lethal to all fish. If your test results showing that you have high ammonia then obviously you need to try and find out why this is happening. Just remember that you pH is closely related to your ammonia so when testing for ammonia you must also test for pH.

This chart will give you an idea of how a tank with varying temperatures and pH ranges affects how much ammonia can be present without killing your fish outright. You can clearly see that water with a pH of 8.5 at a temperature of 25°C becomes that much more toxic with just 0.1 of the total ammonia, whereas water with a pH of 6.5 at the same temperature can contain a lot more ammonia before it becomes lethal. It would be a mistake to suggest that even the less toxic form of ammonia is safe for fish, it is just that it is less toxic than free ammonia (NH3). All efforts must be made to keep the ammonia at minimum levels at all times.

PH and water temperature

Electronic Monitoring of Water Parameters

If you are worried about deteriorating water conditions then there is now a device on the market that will monitor all the major water parameters and if something goes wrong will flash some warning lights. Believe it or not, you can even set this device up to send you an e-mail, or an SMS on your mobile phone, very handy if you are not at home. It could however completely ruin your holiday if you are abroad and receive a message telling you that your ammonia levels are soaring.

This electronic device which is called the and can be purchased at most good fish stores and also on eBay


Slime Coating

When you have toxins such as ammonia or nitrite present in the water you may notice that your Oscar starts collecting very fine dust particles that attach themselves to its body. Basically, your Oscar looks like it's been rolling around in the dust. Fish often develop a protective slime coating when toxins are present. What is happening is small particles in the water that normally get removed by the filtration system are actually sticking to the slime on the fish. This is obviously a good indication that the water quality may not be quite up to scratch.


Talking about pH

Let us briefly talk about pH in the fish tank. The majority of tropical fish can live perfectly healthy lives in a wide pH range. 99% of the time it isn't necessary to make changes to your pH.

The pH is the measure of the acidity in the water. A pH of 7.0 is neutral. Anything higher than 7.0 is alkaline, anything lower in acidic. Oscars like acidic water with a pH level around 6.5 to 7.0. However, they will be okay with levels up to 8.0. However, pH level of 7.0 is ideal.

Don't be alarmed if after a while the pH of your aquarium water differs from your tap water, this probably will happen and shouldn't be any cause for concern. PH normally drops at night, and then rises during the day. It can change when you add fish, or take fish away. Fish waste can have a lot to do with pH levels as well. If you've got a heavily stocked Oscar tank with no plants, you may find that your pH is very low. On the other hand, if you've got a heavily planted tank, your pH levels may be higher. What you have in your tank can influence the pH. You may have heard the word "buffer" when reading about pH. The most common buffer people will have in their tank is wood. Buffers have an influence on the pH, they can either raise it, or lower it. For instance, bogwood has a tendency to lower pH. Some materials such as coral can actually raise pH, people who keep certain types of fish, African cichlids for instance use crushed coral to raise the pH.

If you do want to lower the pH, you can put some peat moss in your filtration. Bog wood also has the same effect but is not quite as efficient. Please bear in mind that wood will stain your water make it look like tea (without the milk). However, give it a couple months and it will clear.

To raise the pH, many people use crushed coral. You can also use limestone as decoration, this will also raise the pH. You have to bear in mind that this is not a quick way of doing it, it will be a relatively slow process.

If you do have wood in your tank then your pH is going to change whether you like it or not. Trying to change your pH using chemicals should be an absolute last resort. You should only attempt this if you have a good knowledge of water chemistry. Using chemicals when you don't know what you're doing could render the whole system unstable. Basically this means that pH could drop off the scale at any time.

The one important thing to remember is when you carry out water changes.  If the pH of your aquarium water differs a lot from the tap water, you would be wise not to carry out very large water changes.  What you don't want happening is large fluctuations in pH, this can often shock fish and even kill them.


PH and Its Relationship to Ammonia & Water Temperature

It is important that you have means of testing the pH of your aquarium water. The toxicity is greatly related to the pH of your water. To a lesser extent the temperature of the water also plays a role in how toxic ammonia will be. At the temperature of 28°C (82°F) with a pH of 7.0 and 5 ppm of Total Ammonia Nitrogen present, you only actually have 0.3 of ammonia in your water. A pH of 6.0, 28°C with 10 ppm of Total Ammonia Nitrogen means your ammonia is actually 0.007 ppm. If we go in the opposite direction, a pH of 9.0 with 5 ppm of total ammonia nitrogen present would mean you actually have 2.06 ppm of ammonia in your water, this is extremely toxic and would probably kill fish in a few days.


Test your Water

 Anyone who keeps aquarium fish at home should also know how to test the water if anything goes wrong. Testing aquarium water is actually very easy and only takes a couple of minutes at the most. Being in the position to test your own aquarium water can often be the difference between saving and losing your fish completely. Some people rely on the fish store to test their water for them. That's all very well but what happens if you have a crisis at 10:30 PM on a Sunday evening? The fish store is not going to be available for you to take a sample of water is it? If one of your fish becomes ill, or the water in the aquarium doesn't look right you can often get an idea of what is going on by testing the water. Water testing kits will be available at all good fish stores. I'm not going to pretend they are cheap, they will cost you a few quid for the four main kits that we recommend people own. They are ammonia, nitrite, nitrate and pH. Ammonia and nitrite is highly toxic, you need to know straightaway if these two toxins are present in your aquarium water. Nitrate must be kept at a safe level so as to keep your fish healthy. We recommend testing your nitrate at least once a week. An unbalance of pH can have a devastating effect on your aquarium so even though many people don't think this is important, it is actually vitally important that you own a pH testing kit. We would recommend that you get into the habit of testing the pH of your aquarium water occasionally until you know exactly what happens after water changes which can often have an effect on pH. 



Nitrate is a byproduct of ammonia and nitrite. Your biological filter will turn ammonia into nitrite, then a similar process will convert nitrite into nitrates. Now whereas ammonia and nitrite are absolutely lethal to fish, even at very low levels, nitrate is not anywhere near as toxic. In fact, fish can survive in nitrate levels up to 100 ppm without showing any side-effects. Now I'm not suggesting you keep your fish in these conditions, nitrate is still dangerous at high levels and will cause fish to become stressed. When fish become stressed their immune system can become compromised and make them more susceptible to disease and illness. 

  • Overstocking your aquarium will almost certainly lead to high nitrates. An aquarium that contains too many fish will almost certainly contain amounts of nitrate that far exceed safe levels. Stocking your fish tank sensibly is the best way to stop the nitrate levels from rising too quickly.
  • Overfeeding is also a major factor in encouraging high nitrate.  The more the fish eats, the more waste it produces. Fish will eventually become full so any left over food that is not removed from the aquarium will eventually contribute to nitrate levels.
  • Decaying plant matter is something many people overlook. Dead plants will slowly rot producing ammonia which we know will then eventually become nitrate. If you keep plants in your aquarium then it's very important that you look after them properly, remove any dead or decaying plants immediately.
  • Remove any dead fish, don't just leave them in there in the hope that the other fish will eat them. Dead fish will rot in the same way plants do which will all contribute to the nitrate levels.
  • Dirty filters can also contribute to excessive nitrates. Your filtration isn't only there to remove ammonia and nitrite, it also functions to remove solid waste. Solid waste that collects overtime will eventually start producing high levels of nitrate. So even though we don't recommend over cleaning your filtration system, it is very important that you clean the mechanical filtration on a regular basis and make sure that no solid waste has built up inside the filter.


Keeping Nitrates under Control

Now our basic biological filter is not designed to remove nitrates from the water. There are nitrate filters available that will keep nitrates under control. I've always been somewhat dubious about using these as I think it could encourage people to become complacent about water changes. Water changes are still necessary as you will need to replace minerals in the water that will slowly disappear in the aquarium. The easiest and cheapest way to keep nitrate levels under control is by pure elbow grease, in other words get your bucket or hose out and change the water manually. It is very important that you carry out regular and frequent water changes, rather than doing one massive water change every few weeks. Small frequent water changes will keep nitrate levels under control, but it will also reduce the chances of shocking your fish. The problem with replacing large amounts of water in one go is you can often change pH levels very quickly which is extremely dangerous to your fish. In a properly stocked fish tank you really shouldn't have to change any more than one third of the water each week. If you find that your nitrate levels are extremely high and you are having to change more than half a tank of water each time then it's probably time to start asking yourself why this is happening.

For those of you who have got new aquariums and are getting used to how things work, I would recommend you carry out a weekly nitrate test until you get used to how your water conditions behave. I would recommend you get yourself a good quality V that will give you accurate results.


Do Fish Really Grow to the Size of Their Tank?

It's been a common belief that fish grow to the size of their tank. Actually this is completely wrong, fish will grow to a size that fits their species. I'm sure that you have seen shoals of mackerel or sardines, all of the fish are basically the same size, Oscars are no different, they will more or less reach the same size as adults. You may find that you come across individual fish that are unique and reach sizes that exceed what we would consider the norm. There are various factors which could under certain circumstances affect the way fish grow. Oscars that are housed in very small tanks will often be exposed to polluted water. Prolonged exposure could damage the fishes immune system which in turn could halt the fishes growth. This is probably where the term "growing to the size of their tank" comes from, people who have not housed the Oscars in an adequate and suitable environment.


Gravel vac

There are various products on the market that are designed to help you with water changes. One such product is called the . The way this works is that you connect it to your tap and then turn the water one. What happens then is that the strength of the water coming out of the tap causes a siphon so you can vacuum the tank. There are a few drawbacks with the rest of us. Firstly, if you don't have a strong water flow coming out of the tap, the suction will be very low and you won't be able to suck up big bits of debris. Secondly, if you are on a water bill, it could get very expensive because not only are you running the tap to take water out, you have got to then put water in. And finally, do you really want all that crappy water going into your sink, especially if it somewhere that you prepare food? I have tried the Python and it failed miserably. I personally don't think that the Python is worth the money. Lots of people rave about it so each to their own. I much prefer using a hose and gravel vac. Certainly a lot cheaper and does exactly the same job.


Battery-operated gravel vac

There are some fancy gadgets on the market that are made for cleaning aquarium substrate such as sand and gravel. You can get battery-operated gravel vacs on eBay.


Cleanings Substrate [Sand & gravel]

Cleaning sand is probably the easiest thing you'll ever do. With sand, dirt doesn't normally work its way underneath because of the particles being so tightly packed together. For this reason, the dirt normally sits on top. This means the filters will have more chance of removing it. When cleaning sand, you literally hover above the surface of the substrate. Just close enough so that the suction lifts the dirt and removes it from the tank. Make sure you disturb the stand a little as well so to release any dangerous gas pockets. You may get a bit of sand churn around in the vac, it doesn't normally get sucked out if you lift the vac up straight away and let the sand fall out.

We've looked at sand and how to clean it. We will talk about gravel on how to clean it now. With gravel, there is more space in between the particles, unlike sand. This means that debris works its way under the surface a lot easier. This has both advantages and disadvantages. The biggest advantage being that you can't see a lot of dirt meaning your tank looks cleaner for longer. The disadvantage of this is if you don't clean it properly, you can get toxins building up in your tank because of the trapped dirt that is encased in the gravel. You clean gravel in the complete opposite way you clean sand. Push your gravel vac as far as it will go into the gravel. They are normally made of clear plastic so you should observe murky water as the dirt is lifted from the gravel. When the gravel vac clears, lift out, and carry on doing the rest of the tank. There is one important thing you must remember, substrates, especially gravel will have beneficial bacteria living amongst it, so for this reason, you don't want to go over the top when cleaning. Just get the majority of the dirt out. Over cleaning will just remove a lot of the beneficial bacteria which could have a negative affect on how your tank deals with all the toxins.


Healthy Food

Various cichlids, especially Oscars are susceptible to a particularly nasty disease called hole in the head. You may also see it written as HITH. There are various things you can do that will help stop this disease developing. The two major causes of hole in the head are a poor diet and poor water conditions. Oscars have a varied diet in the wild. They don't just feed on fish as many people think. 60% of their diet is made up of insects and crustaceans. You shouldn't feed your fish entirely on feeder fish (a feeder fish can be anything from a goldfish to a tetra) If you do want to feed them fish, limit them to a few fish a week and it is probably best if you breed them your self. Feeder fish that are purchased from fish stores have in some cases had a pretty hard life, they may have been kep in poor water conditions and shipped from pillar to post. Occasionally, they may well become so stressed, they develop diseases and illnesses. You really don't want to be feeding diseased and ill fish to your Oscar. Doing this could contribute to the illnesses such as hole in the head disease.


Saturated Fats

Don't be tempted to feed your fish on meat such as beef or bacon. These sort of foods contain saturated fat which is very bad for fish. A fish's liver cannot process saturated fat very easily so long term feeding of foods high in saturated fats should be avoided. If you want to give your fish meat, make sure it is very lean indeed. You are probably best off buying ready prepared meat from the fish shop. You can always make your own beef heart if you are feeling adventurous.


Vitamin Supplements

A varied diet is an important factor in keeping your fish healthy from disease and illness. The lack of some vitamins such as A, B & C can result in such ailments as poor growth, eye & skin problems, plus more serious problems that can affect the gills and spine. Feeding your fish on a healthy varied diet should ensure they receive all the correct vitamins. You can always supplement their diet with vitamins that can be added to food such as blood worm and other frozen foods that will soak liquid vitamins up. You can also makeup foods such as beef heart and add your vitamins to this as well.

I actually use a product called Atvitol. However, rather than adding it to my fishes food which would be difficult, I add 30 drops every day to the aquarium water.

Atvitol helps maintain the aquarium with vital elements and bio-elements. It protects fish against diseases, enhances the brilliance of colours, encourages spawning, increases appetite and promotes natural growth.

The addition of Atvitol to the aquarium also provides the microorganisms necessary for the breakdown of biological pollutants with active substances. This provides the best conditions for biological filtering.

Can be added to either the food or water for amazing results.

Can be used in both tropical and marine aquariums.


Oscar Is Sulking, Lazing around, Stressed

It is not uncommon for Oscars to appear to have a little sulk.  From my experience it normally happens when you are carrying out water changes.  Some Oscars don't appreciate what you are doing for them and can get fairly angry if you start sticking gravel vacs into the tank.  Sometimes they will either retreat to the back of the tank, huddle together looking rather sorry for themselves, or they may even attack the gravel vac.  You may notice your Oscar resting on the bottom of the tank leaning to one side, this is also not uncommon and as long as they don't do it for too long, is certainly nothing to be concerned about.  If your Oscar is stressed for any reason they may retreat to a corner of the tank and stay there for a while.  Again, as long as your Oscar doesn't behave like this for prolonged periods, it isn't a cause for concern.  A healthy Oscar will be on the move most of the time and only when they are sleeping will remain motionless for longer periods of time.

Alarm bells should start ringing if your Oscar lays on its side breathing heavily and basically doesn't do anything including eat. This would be a sign of a sick Oscar and unfortunately in many cases by the time they start behaving like this, it's too late to save them.


Aquarium Salt

It's been common practice over the years to add salt to a freshwater aquarium on a regular basis. In recent times people have now started saying that salt may actually cause more harm than good. Salt can have benefits when treating certain ailments, Epsom salts for instance are often used in conjunction with pellets to treat internal conditions. If you want to use salt then make sure you use the correct measures. You must use one tablespoon per 5 gallons of water and no more. Always check that the fish you are keeping can tolerate salt as some fish do not like salt as it can irritate their skin.


Cuts Abrasions & Damaged Fins

Something that you will have to get used to when keeping Oscars is that they have a tendency to bash themselves up occasionally. I have yet to keep an Oscar that hasn't either injured itself while squabbling with another Oscar, or swam into an object in the tank. As you can see by the photo, this juvenile Red Oscar has quite a nasty looking abrasion on its head. In fact, the top layer of skin is missing altogether. This probably happened at night as I noticed it in the morning. It probably swam into a rock or maybe the side of the tank.

It can be quite upsetting for newcomers when they see these sort of injuries for the first time . Let me reassure you that in most cases these injuries whilst looking quite serious, are actually very superficial. There is no need to medicate the tank, just keep your water in good condition, that means nitrate should be kept as low as possible. Doing this often helps the injury to heal reasonably quickly. if the injury looks particularly nasty, or isn't healing in a reasonable time, you could treat the tank with a medication such as melafix. There is more information on this website about medication and cures, it's always a good idea to know what medications are available and what they do should problems arise. The photo to the left shows the same Oscar. You can clearly see that only three days after receiving the injury, the wound is healing nicely

Occasionally an Oscar will damage its fin. The pectoral fins which are on the side of the Oscar are quite vulnerable. The Oscars tail can often get damaged, often you will see a split. Again, these normally heal up reasonably quickly so don't worry about it. Like what I said about abrasions, if the Oscars fin/fins don't start healing in a reasonable time, have a good look at them to make sure that there is no bacteria or fungus forming where the damage is.

Oscars are very good healers, but only if your water is in very good condition. As you can see in the photograph above, one of my Oscars sustained quite a nasty injury by swimming into something in the aquarium. The after photo shows the wound about one month after the incident, a few months on the wound has healed up perfectly without any scarring whatsoever. Having said this, some injuries or very bad cases of hole in the head disease can leave slight pitting or scarring when healing is complete.



What is bacteria? Bacteria are single celled organisms that are microscopic, i.e. invisible to the naked eye, you can only see them with the use of a microscope. For this reason, treating bacteria infection in fish is notoriously difficult. If your fish develops a bacteria infection, you may see one, or several symptoms. These could be swelling of the abdomen, white feces that floats, or appears to be very stringy and trails behind the fish. Bacteria infections can also result in skin problems such as slime. It is worth noting that most bacteria is totally harmless, in fact, a lot of bacteria is absolutely necessary for life to exist. You need bacteria in your filtration system, without it, your fish would not be able to survive.

Outbreaks of bacteria infections in an environment such as an aquarium are nearly all caused by pollution. Remember that an aquarium is a huge compromise to the wild. In the wild, you would have so much more water to dilute problems that may occur. You will have natural filter systems that remove all the nasty stuff. In an aquarium that is not maintained properly, you'll just keep building up lots of nasty organisms which if left unchecked, may cause serious problems.

If you suspect your fish does have a bacteria infection, you may need to try several medications before you find one that works. Some medications may need to be ingested, i.e. the medication will only work if it is inside the fish. You can soak fish food in antibiotics, this is the best way of administrating medication to fish. However, this is sometimes not possible if the fish has stopped eating, this often happens when the fish has an internal bacteria infection. In cases like this, a visit to a professional veterinarian is essential as they may be able to administer the drugs by injection.

You must remember that if you do use the medication and it doesn't work, carry out a large water change before medicating the tank again. Alternatively, use some good quality carbon in your filtration system, but remember to remove it before medicating the tank again. Also bear in mind that a clean aquarium is essential for medications to work successfully. It is a complete waste of time medicating a dirty aquarium, this will prevent the medications from working properly.

Good tank maintenance is the key to keeping your fish free from bacteria infections. If you are the sort of person that is lazy and cannot be bothered to do water changes, then don't be surprised if your fish start becoming ill.



Parasites can be troublesome if your fish has been infected. If not treated properly, they can often lead to death. There are many types of parasites that can infect fish, both external and internal. Typical symptoms that point to your fish having an internal parasitic infestation may include yellow or green faeces, sometimes the fish may have white stringy poo which some people compare to cotton or dental floss. Internal worm infestations may result in your fish becoming bloated, lethargic, lose weight, and sometimes more seriously develop a blocked intestine. Sometimes you may see worms protruding from the fishes anus. 

Hexamita is a parasite that lives in the intestine of some species of fish, including Oscars. Under certain circumstances such as when your fish has been put under stress, this parasite can migrate to other parts of the fishes body and start causing serious problems. Symptoms may include signs of hole in the head disease, dramatic darkening of the fishes body and possible slimy faeces. The fish may start hiding in corners with his head pointing downwards. You may notice that the fish tries to eat but splits the food straight back out again.

Larger external parasites are often visible to the naked eye. Anchor worms, lice, leeches, cysts connected to white spot disease are quite easy to see. Typical signs of an external parasitic infestation is when you see your fish rubbing (also known as flashing) themselves against rocks, or substrate. The fish may also develop red patches and inflammation its body. These are often found at the base of the dorsal fin. Breathing may be laboured and the fish may become lethargic. Because some parasites penetrate the fishes skin, bacterial ulcers may break out. It is important to mention that the symptoms mentioned here don't always mean your fish has a parasite. Your fish may have developed another disease or poor water quality could be irritating them.

External parasites can be treated with various medications that can be simply added to your aquarium water. However, if your fish has developed internal parasites then the medication has to be ingested. There are various medications on the market that you can simply add to food. Some medications in the UK are not available off-the-shelf, you will need to go to your veterinarian and get them prescribed.



One of the most common parasitic infections that often affects tropical fish is called Whitespot, or Ick. This parasite is very contagious and can also attack stressed fish. Fortunately it's not a difficult parasite infection to eradicate. We have an article that will give you all the information you need to get rid of white spot if one of your fish becomes infected. The photo above shows a Neon Tetra that is affected quite badly with the white spot parasite. More info on treating white spot


Popeye Disease

Another one of those diseases that seems to crop up occasionally. Popeye disease can be caused by a variety of factors such as a bacterial infection, poor water quality and a parasitic infestation. This disease has very obvious symptoms. One or both eyes may appear very swollen and protrude from the side of the head. Unless you are not a very observant person, you really can't miss this symptom. It is worth noting that Popeye is rarely fatal. It may only persist for a short time and then go away again. However, action needs to be taken for the sake of the fish. There are various medications that can be used to treat this disorder, one of them is called myxazin and should be readily available at your fish store.


Fungal Infections

Fungal infections are quite obvious when they occur, the fish will develop obvious signs of cotton wool growth on any part of its body, including eyes and fins. The colour of the fungus can be white, grey or brown.  Fungal infections will often occur if water conditions are poor. Fungal infections can also develop around cuts and abrasions.The best way to avoid fungal infections is to keep your water in pristine condition all the time. There are various treatments available, your fish store should be able to supply you with a treatment that will work for you. However, a popular and well tested treatment is called Pimafix, manufactured by aquarium pharmaceuticals. Many people have used this medication with great success.



This condition is usually caused by a bacterial infection. Fin rot will normally cause the fins to split, or become ragged. Severe cases will totally eat away the fin until there is only a stump left. There is often a white egg edge to the affected area. There are treatments available for this condition, which are normally antibacterial medications. It's worth mentioning that this condition is often caused by poor water quality so keep up with your regular water changes. If your fish store sells Myxazin then this is a popular treatment for this condition.


Medications for Tropical Fish

Please visit our page on treatments and medications as we have listed various medications that are readily available at most fish stores and online


Oscar Fish is Breathing Heavily

Breathing heavily, gasping, rapid gill movement, these are signs that something may not be quite right in your aquarium. A fish should not look as though it is fighting for oxygen. Obviously it will have to open its mouth but it shouldn't be a constant opening and closing motion. If you notice that you Oscar has started to struggle with its breathing then there are a few things to do at first. Firstly is your water in good condition? Check for ammonia, nitrite, nitrate and pH. If your water checks out okay make sure that your tank is being oxygenated probably. Check whether water is coming back in from your filtration, is it creating surface agitation? If not, it could just be a case of lack of oxygen in the water. If indeed this is the problem then all your fish will probably be behaving in the same way. Adjust the pipe and if all the fish stop breathing heavily you know what the problem is.

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You may notice your Oscar Fish yawning in very much the same way as we do. However, it's not fully understood why fish yawn, it's certainly not for the same reason we do, that is for sure. It's thought that fish may yawn to dislodge an irritant that has got stuck in their gills which are very sensitive. Yawning can also be a sign of poor water quality such as high nitrate, ammonia or nitrite. Some people have suggested that the fish may be stretching the muscles within the jaw when they yawn. If you see your fish yawning on a regular basis then it's probably a good idea to run some investigations into water quality.



It is not unknown for fish to suffer from constipation. In most cases the condition isn't too severe so there's not too much to worry about. You may find that a swelling develops around the anus area on your fish. This swelling can often get quite large, I've seen swellings that have approached the size of a chickpea. Normally this will last for a day or two and then the Oscar will produce a massive poo and everything will go back to normal. However in some circumstances the blockage is a little more serious. If you believe your fish is constipated then cease feeding straightaway, there's no point in getting it to eat more food if it can't get rid of the waste, that will only add to the problem. If after a day or two the problem resolves itself then there's nothing more to be done. Adding garden peas to your fishes diet is often an effective way to relieve constipation. If the problem doesn't go away then you may have to try another method to relieve the constipation. Epsom salts can sometimes be an effective method at relieving constipation in fish.

Dosage and Administration

1 level teaspoon per 4 gallons of water dissolved in a small volume of aquarium water and then added to the aquarium. Depending on what the temperature of the water is, you can raise the temperature slightly will increase the fishes metabolic rate. If your aquarium water is already very warm then ignore the last comment.


Lump on Oscars Lip

At some stage, you may notice what looks like a pimple, protrusion, call it what you like on your Oscar's lower jaw. This is something that is quite common with Oscar. They normally start appearing when the Oscar is around five or 6 inches long, sometimes a little earlier. People have various suggestions to why they develop these strange lumps. Cleaning rocks and shovelling gravel is probably the most common suggestion. However, I don't think that this has anything to do with this lump on the jaw. I believe this is just something that develops as the Oscar approaches maturity. So if you do see this lump one day, don't worry yourself.

My Oscar Changes Colour

Colour changes in the natural world is quite normal. Many many creatures are able to change colour for various reasons. You only have to look at squid to understand this. Fish change colour for various reasons. If you have your Oscars for long enough, there is probably an extremely good chance you'll see them change colour at some stage. Let me first say that baby/juvenile Oscars are always a different colour to when they are adults. So as they grow older, expect them to change colour, sometimes dramatically, especially with Tiger Oscars.

What you have in the tank can also cause fish to change colour occasionally. The backgrounds, substrates can often influence a fishes colour at times. I found that my fish would sometimes become very pale when first putting lights on with the white sand. Sometimes the colour changes in the red Oscars was quite dramatic. They would sometimes go from quite a vibrant red to almost no red. My clown Loach change colour quite often. When they are fighting, their body colour changes to almost black, pretty amazing for a fish that is actually yellow in part. Oscars do this as well, if they are angry, spooked or when they are breeding, they often change colour. Tiger Oscars are one of the most amazing fish for colour changes. I was amazed how different my Tiger Oscar looked when he used to change colour. However, they should always return to their normal colour. If your Oscar is stressed, it may slowly turn very dark in color, sometimes becoming almost black. Normally it will become very subdued, stop eating and basically look very sorry for itself.

It is always handy to have a hospital tank that is fully cycled and ready for any ill fish. If one of your fish is showing signs of illness than it is always a good idea to transfer it into a hospital tank. Sometimes the fish doesn't show any external signs of illness apart from changes in colouration. If the fish regains its colour after being transferred into the hospital tank then you know that there are problems in your main tank.


Moving Your Oscar

I thought I would say a little bit about moving oscars from their tank. The best thing to do is take water straight from the tank so that it is at the correct temperature. Now, getting a sizeable Oscar out of the tank can be a very wet job if you dawdle and take your time. Make sure you've got a big net for a start. If you can't catch Oscar in the first three of four minutes, rest up for a while because you don't want to stress the fish out. Once you have cornered him and he is in the net, be very careful when you lift the fish out, they will thrash around like nobody's business. The best thing to do is when you've got the Oscar in the net, lift it out of the water straight away. Most people start panicking, instead of lifting the Oscar straight out of the tank, they hold it half in and half out of the water. Doing this wil almost guarantee a soaking for anyone within 6 ft. of the tank. The chances are, you will have water up the walls as well. You also have to be a bit careful that the fish doesn't bash itself as you are lifting it out of the tank. Just take your time and everything should run smoothly. I've often heard of people using towels/pillowcases that they place in the tank and then heard the Oscar into the towel/pillow so the fish can then be lifted out. Other people use small buckets that they lower into the tank. They then manoeuvre Oscar into it. I haven't tried either of these methods, I find using a suitable net about the easiest way of transferring Oscars


Hospital Tank

One of the biggest drawbacks with having a very large aquarium is when it comes to medicating it. Medication is not exactly cheap so if you have got a 100 gallon + aquarium then it could get rather pricey if you need to medicate for any reason. Also if one of your fish develops a contagious infection such as whitespot/Ick then it is always a good idea to try and isolate the fish so you can contain the infection. If you have got some space then a hospital tank can often be advantageous. Hopefully your fish will not be spending too long in your hospital tank so it doesn't have to be very big, normally between 20 and 40 gallons will suffice. The filtration on your hospital tank should be very good as medication will not be so effective if water conditions are poor. You shouldn't really treat it any differently to your main aquarium, after all the hospital tank is going to be considerably smaller containing much less water. I would recommend that you do not feed your fish whilst it is in the hospital tank, you want to reduce the amount of waste that the fish produces whilst it is in isolation. However even though a fish may not be eating, it will still produce ammonia through its respiratory system so good filtration is necessary.

You don't need anything in the hospital tank such a substrate or ornaments, these will only take up valuable space where you really need water. One important factor to bear in mind is how do you keep your biological filter healthy and alive? You never know when your fish are going to become ill and it does take several weeks to cycle a tank, even a reasonably small one. You have two choices, you could either keep some fish in the hospital tank so that the bacteria always have a food source, or alternatively you could keep a spare filter running on your main aquarium. Another option is if you are running a sump filter, you could actually take some media from the sump and put it in your spare canister filter. If having a hospital tank is not an option and you have no choice but to medicate your main tank always read the instructions on the medication very carefully as some treatments can damage your biological filter, the last thing you want to do is destroy all your bacteria, you would then be in real trouble.


Humanely Euthanizing Fish

At some time in our lives, most of us have had cats, dogs etc that either become ill, or reach the end of their lives. Sometimes they die a natural death, on occasions you have to help them on their way as this is the kindest thing to do. Oscars can live for 15 years so you will become very attached to them. Their time will come and sometimes euthanasia is the only way out of a horrible situation.

Most of us have heard stories of flushing fish down the toilet. This is totally inhumane so don't ever do it as the fish will not die very quickly. Anyway, even the largest turd won't come close to a large adult Oscar so don't try flushing these down the toilet. You'll only end up having to call out Dinorod to get your drains unplugged.

Those of you who fish for the table will no doubt have knocked a few fish on the head in your time. Obviously, if you've got the confidence, a swift blow on the back of the head will dispatch a fish very quickly, but it must be done precisely or you just might stun the fish rather than actually kill it. Having said that, I would be hard-pressed to be able to do this to a long standing pet, but that's just me. A sharp knife through the back of the neck is also a proven way of killing fish but again, very gruesome. Breaking the neck, liquidising the fish, freezing, chopping the head off. All will kill fish but would you want to do it? Probably not. The best and humane way of euthanising a fish is to give it an overdose of anaesthetic. Now, this is not as straightforward as you may think. Attempting to euthanise a fish without the proper experience could result in unnecessary stress to the fish. When I had to euthanise my large tiger Oscar, I called upon the services of a good friend of mine who is an experienced koi carp enthusiast. He has used anaesthetic many times and knew exactly what to do. My tiger Oscar was put to sleep quickly and humanely without any stress whatsoever.

Now, if you are not able to find anyone who can do this for you, there is another option. Clove oil can be used to euthanise fish when used properly.Read Full Article on how to use Clove Oil ...

Since the Internet has come along, hundreds of different fish forums have sprouted up. The majority of them give good sound advice and help a lot of people. I hope that I can include this website

To treat many fish diseases properly, you need to know what you are dealing with. There is an unbelievably large amount of different viral/bacteria/fungal diseases in the world, many of which will affect aquatic creatures such as fish. In a lot of cases to find out exactly what your fish is suffering from would mean taking samples of skin and even blood. These samples would need to be to be tested. It could then be determined what kind of treatment is needed. A lot of medications have to be injected, not the sort of procedure many hobbyists would be willing to undertake. So you can see that it is not always as straightforward as asking a question and getting a reliable answer from us. At the end of the day it all boils down to how much you love your fish, and how far you want to go to, and how much money you are prepared to spend to cure it , and hopefully save its life.

Finally, I would strongly encourage any aquatics enthusiast to purchase a really good fish health book. Even if you do you consider yourself to be very knowledgeable, you can't possibly know everything about fish health. I myself have a copy of The Interpet Manual Of Fish Health. It is a very informative book with lots of photos which are always very helpful. These are absolutely invaluable and often save you the bother of getting totally confused by dozens of different diagnosis given by people who at the end of the day, are just guessing in many cases, and I mean no disrespect by that comment.

This page is intended to give you advice and help on how to keep your Oscar healthy. Any health-related advice on this websit is intended as a guideline only. I and many of our members are not trained professionals. For a reliable diagnosis on a health issue, please seek professional advice from a trained vet.

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