Bloody greedy Oscars. You should see my freezer, it’s got every conceivable type of fish food you can think of, frozen fish, krill, bloodworm, cockles, muscles, just to name a few. And what does one of my red Oscars decide to eat? One of my bristlenose catfish. Or rather, chew on its head a little bit and then spit it out when he realizes it’s just too big to swallow it.

So there is a lesson for you all here, Oscars will try and eat just about anything that will fit in their mouth. This bristlenose catfish was 4 inches long, or thereabouts. I honestly didn’t think the Oscars would bother with it, how wrong could I have been?

I’ve thought I would try and clear up some confusion when it comes to calculating how much water is in a fish tank. When you calculate how much water a fish tank contains, you have to take into account how long it is, how wide it is, and how high the tank is.I know that you should take into account substrate, ornaments etc, However, for the sake of brevity, we are just going to talk about the tank. So for instance, let’s take my 6′ x 2′ x 2′ tank that contains two red Oscars. In inches, that is 72″ x 24″ x 24″. Run that through a tank calculates and it tells you your tank is 150 UK gallons, that is around 180 US gallons. Now, have a look how far the water comes up the tank. In other words, if your tank is 24 inches high, does the water come up 24 inches high? In some cases the water will actually be three or 4 inches below the top of the tank, that may not seem much, but believe me, this will make a big difference to how much your tank actually holds. It is very important that you know you how much water you have in your tank. If you think you’ve got 180 gallons, when in fact you only have 150, you could easily overstock your tank. You also need to know how much water you have when medicating a tank. Again, if you think you’ve got more than you actually have, you could easily over medicate a tank which could put your fish at risk in some cases.

I thought I would add something to the blog that will hopefully help newcomers avoid the same mistakes as nearly every fish keeper has made in the early days of keeping fish. We’ve already talked about changing water in tanks etc.

I’m not going to go down that road again, what I want to talk about is cleaning your filtration system. If you’ve read the website properly, you will know that most filters consist of two types of media. These are biological, and mechanical. Mechanical filtration is what catches all the debris, that will be fish poo and uneaten food, and maybe other little bits that may be floating around in the tank. Mechanical filtration normally consists of a sponge material. Depending on how big your filters are, how big the tank is, and how many fish you’ve got, mechanical filtration will need rinsing out every now and then. Whereas it’s okay to do this under the tap, I would actually advise you to do it in existing tank water. Even though it’s called mechanical filtration, you will get bacteria living in it, so you might as well try and save them. Now what’s the difference between tap water and your existing tank water? The tap water will contain chlorine. Chlorine will destroy bacteria, please remember that. Now let’s talk about biological filtration. This is what keeps your tank alive, without a healthy bacteria colony, your fish would end up swimming around in a toxic soup, rather like you taking a bath in the cesspit. Actually, they wouldn’t be swimming very long because they would all die. So for this reason, it is vitally important that you treat your biological filter extremely carefully, failure to do this will result in all the bacteria dieing, then you will be in trouble. Dangerous toxins would start building up in your tank and your fish could well be put at risk.

Biological media comes in quite a few forms, some are just plain old sponges, other times they are ceramic type material which often resemble dog biscuits, or even pasta. You will have to give your biological media a wash every now and then. Now this is very very important, you must not going to the top when cleaning your biological media. When you clean you bio-meadia, you don’t want to end up with shining biological media that looks like it’s just come out of a packet, you want it to look grubby, a little bit on the dirty side. Some media, like bac-balls always look clean, don’t let that fool you, there will still be a nice loss of bacteria living on them. These probably will not cleaning as they normally reside in a large sump filter. I have got a couple of Eheim canister filters that contain ceramic type material. When I clean this type of material, I remove the trays and then pour the media into one of those strainers that you put vegetables in to get rid of the water. I then dunk this into a bucket of existing tank water just to remove any surface crap and that is all.

So that’s it really, it’s not rocket science. A couple of other points before we finish, never ever let it dry out, that will kill the bacteria straightaway. Try not to leave your filters off for more than one hour, biological bacteria need oxygen to survive, basically the movement of the water running through the filter provides them with this. As soon as the water stops running, oxygen depletion will set in.

Remember, your biological filter is your best friend, look after it

I’ve come across various discussions on some Oscar forums that talk about the possibility of keeping Oscars in tanks as small as 5 gallons. Now I’m not going to get into the ins & outs of how this can be done because quite frankly I think this kind of experimentation will only help to encourage people to try and keep Oscars in totally unsuitable environments. You can go on any forum that has an Oscar discussion section and you will read countless threads of people who are keeping Oscars in very small tanks, the majority of the time they are seeking advice on health issues which isn’t surprising. We do try very hard to educate people on how to look after an Oscar in a responsible manner. So why have we got people experimenting on keeping Oscars in tiny tanks? Would you buy a horse and keep you in a stable for its whole life? I’m quite sure that you could keep it alive by feeding and watering it, but would it be truly happy never being able to run around the field? Oscars are large fish, they need the freedom of a large aquarium to move around in. Now I am quite skeptical to whether fish possess emotions that can be compared to humans or dogs and cats for instance, but my Oscars seem happy and contented in both their six-foot, and eight-foot tanks. This is probably due to the fact that they can swim back and forth without bashing their heads against the side of the tank.

You have got to remember that the Oscar comes from the largest body of fresh water in the world. They are certainly not the biggest fish you’ll find, however they do have the potential of getting quite big. Shouldn’t it follow suit that you prepare yourself for this eventuality? I know that 99.9% of captive Oscars have been interbred to produce different species and have never seen the Amazon, however they are still the same fish which in theory require the same conditions to live in. Now all of a sudden we have people saying, “hey, it might be possible to keep an Oscar in a 5 gallon tank if you carry out a water change every day” well I’m saying, I’m sorry, under no circumstances should you keep an Oscar in a tank of this size”

But at the end of the day, this is just my opinion.

I often get questions about feeding meat to your Oscars. I would actually advise you not to feed meat to your Oscars, unless it’s properly prepared lean meat from a fish store such as beef heart. Most animal meat contains saturated fat. It is suggested that a fishes liver does not process animal fat very well, animal fat can actually damage a fishes liver. This evidence is backed up by the fact that a lot of commercial carp fisheries have now banned the use of commercial trout pellets on their fisheries. These type of pellet are used to fatten up trout and salmon and therefore contain high levels of animal fat.

You’re better off giving your Oscars properly prepared frozen fish/shrimp/krill rather than giving them meats that may be leftover from your meal.

The Oscar can be classed as quite a unique fish. They appear to be quite social, often interacting with their owners and almost appearing to show fondness, although I think that is taking it a little bit too far. However, the Oscar is definitely not like a lot of other fish that we keep in our aquariums. There is one thing that many Oscars have in common, they do have a tendency to get a little upset at times and more often sit on the bottom of the tank and sulk. It doesn’t take a lot to upset an Oscar, even down to not getting the food they are used to can upset them, rearranging their tank, water changes and many other factors often play a part in an Oscar getting a monk on. I’ve often read of Oscar sulking for days, or even weeks at a time, I would dismiss this as being nothing more than over exaggeration. An Oscar that is kept in the correct environment and is being fed a suitable diet will not hang around on the bottom of the tank for long. Yes, Oscars do get upset, and yes they can sulk, but they will not do it for more than a few minutes. If your Oscar is sitting on the bottom of the tank for days at a time then I would suspect there may be an underlying problem that is causing your Oscar to behave like this.

Once your tank is set up, there isn’t really any reason to disturb the Oscars by moving things around, apart when you’re cleaning. The majority of Oscars won’t sulk or get upset, they will just live their lives eating, breeding and just being Oscars.

It’s always nice to have a variety of fish to add different colour and movement. If you’ve got an Oscar/s then choosing tankmates must be thought through very carefully. Whereas I would disagree with people who class Oscars as ferocious killers, they can however have a nasty side to them. They are large powerful fish that can easily cause great harm to other fish if they want to. So armed with this knowledge we must select suitable tankmates that can live in harmony with Oscar. You want to be choosing fish that are capable of defending themselves, or are quick enough to get out of an Oscars way and very importantly, can easily compete for food.

Before you even think about adding more fish to go in with your Oscar you must determine whether your aquarium is big enough to accommodate any more fish. Now I am not going to go through every tank size there is available, I will leave it up to your discretion to decide whether or not you have enough room for an Oscar and other fish. There are actually lots of fish that will make suitable tankmates for an Oscar. Now before you go out and buy the first fish you see, do a little research on it, whereabouts in the world does it come from? What tank requirements does it prefer? Remember that Oscars are South American cichlids that like to live in places where there are lots of dark hiding places, rocks, pieces of wood, overhanging trees. I actually think that you are better off getting fish that like this kind of habitat. My Amazon tank contains nothing but South American fish. They are all at home with dark substrate, rocks and lots of wood and not a lot of lighting. You can mix fish from around the world but you do have to aware that some fish may prefer water that is at the other end of the spectrum to an Oscar. You must also remember that some fish like to live in groups. A prime example would be the clown Loach which come from places like Malaysia and Thailand. Clown Loach do actually make very good tankmates for Oscars because as adults, they are fairly big, they are also quick moving fish that can avoid a grumpy Oscar if necessary. I keep four of them with two Oscars. The tank is set up differently from my Amazon tank, it contains white sand with a few rocks and some pieces of wood. Clown Loach will swim around in shoals in their natural environment and would probably prefer slightly lighter conditions so consider this if you are thinking about getting them.

After a lot of research, I chose the following tankmates for my Oscars. Silver dollars, Severums, Eartheaters, Leporinus and Blue Acara. All of these fish reach 10 inches and upwards as adults.

The cichlid family is huge, they populate many countries of the world. If you are going to mix different types of cichlids, do your research, some of them should not be put together because of aggression problems. One particular cichlid is called the Red Terror. It has a reputation for being extremely aggressive, even to the person who owns it. I would strongly advised not getting these fish as tankmates. On the other hand, Severum cichlids make wonderful tankmates.

Just remember that when fish breed, they can become aggressive. You must take this into account when populating your tank with different types of fish. Oscars can be very aggressive when they are breeding so cramming too many fish into the small environment could be a recipe for disaster.

There are two fish that you often find in fish stores, these are the pleco, and a fish called the pacu. Both these fish can reach in excess of 2 feet and are unsuitable for the majority of home aquariums so I would strongly advise you to steer well clear of them.

Please never go out and buy a fish if you know nothing about them. The key to success is knowing what you are buying. Ask lots of questions about the fish, how big does it get, it is aggressive and so on. If they are knowledgeable, they should answer all your questions regarding tankmates for Oscars.

Hole in the head disease is one of the most common ailments an Oscar will suffer from. The disease is often brought on when the fish suffer stress due to factors such as poor water conditions or an unsuitable diet. Typical signs of this disease are small holes developing anywhere in the head region. This can be on top of the head, around the eyes, around the gill plates, and around the mouth region. Sometimes small rounded holes appear, other times you may get more of a crater affects developing. You must keep a close eye out for these symptoms as taking action when this disease is in its infancy can be the key to curing it.

As soon as you see any sign that may lead you to believe that your fish is developing hole in the head disease, first carry out a water test , tests for ammonia, nitrite, nitrates and pH. A lot of people don’t carry out water tests and only realise they have serious water quality problems when their fish starts developing health problems. A fish will normally only develop hole in the head disease if there has been some kind of problem with the water or diet, it is quite rare for fish to develop serious health problems such as hole in the head if you have always kept the water in good condition. However, it is not unheard of for a fish to develop this disease for reasons that you just can’t fathom. So what do you do if you see these symptoms developing? In many cases increasing your tank maintenance can clear up the early onset of hole in the head disease. Keeping the nitrate levels below 20 ppm is often best way of clearing up hole in the head disease. Even fairly serious cases of hole in the head disease can often be kept under control and even cured just by keeping your nitrate at extremely low levels. However, I don’t want to lull you into a false pretence that curing every case of hole in the head is easy. Really serious cases of hole in the head disease can actually be very difficult to cure and can even be fatal. There are various medications available that can help cure the disease. Some of them can be purchased off-the-shelf from fish stores, others are only available on prescription from a vet. Different countries licence different medications so what is available in the UK, may not be available in the USA. If you need advice on what is available, either come on our forum and seek advice, or visit your vet. Take early action and in most cases this horrible disease can be cleared up.

Most health-related issues regarding fish are related to poor water conditions. If the water in an aquarium is not suitable for the fish them problems will start arising. If any of your fish start showing signs of ill health, the first thing to do is a water test. A lot of people jump straight on the forum and starts asking questions about why their fish have suddenly stopped eating, started breathing heavily etc. With all the will in the world, it is very difficult to diagnose problems unless they are obvious. If a fish does start showing signs of ill health, you must test for a ammonia, nitrite, nitrate and pH. You can then post a thread on the forum asking for advice making sure that you tell us exactly what the readings are. These four tests will tell you a lot about what is going on in your aquarium. I suppose it’s a bit like going to the doctor and having your blood tested. Even if you don’t understand the test results, somebody on the forum will, and therefore will be able to advise on the situation.

One of the simplest ways to keep both fish and your aquarium healthily is to carry out regular water changes. If you are stocking your aquarium sensibly then water changes don’t have to be a chore that you dread every week, you should only have to change a maximum of 30% of the water. If you are having to carry out 50 or 60% water changes every week, you obviously have too many fish, or maybe you need to look at other factors such as overfeeding.

One of the main reasons why we carry out water changes to remove/reduce nitrate levels. Nitrate is a byproduct of ammonia and nitrite. Whereas it isn’t anywhere near as toxic as ammonia nitrite, it must be kept as low as possible. When nitrate levels get very high, it can be very stressful for fish. Stress can be a major contributor to disease and illness. There are many conflicting reports that will lead you to believe that nitrate is a killer of fish if it rises above 20 ppm. This information isn’t strictly true, all it does is worry people unduly. There are a few books and websites around that will give you maximum figures that nitrate level should not exceed. These are between 40 and 50 ppm. Now, 50 ppm is a little high in my books, however, 40 ppm is by no means dangerous to your fish. However, the lower the nitrate levels in your tank, the better. If your tank is big enough, isn’t overstocked and you feed your fish sensibly then you shouldn’t have any problem in keeping your nitrate levels well under 40 ppm for most of the week. I myself can keep nitrate levels under 40 quite easily. At the end of the two week period when a water change is carried out, my 300 gallon tank sometimes approaches 40 ppm but that doesn’t worry me whatsoever.

Because some fish keepers tapwater contains nitrate, they have no choice but to keep their fish in fairly high nitrate levels exceeding 40 ppm occasionally. In situations like this, extra tank maintenance will keep everything under control. Like me, my tapwater contains no nitrate at all. It is actually a very good idea to test your water for toxins, you can save a lot of frustration if you are getting unsuitable readings and you can’t work out why it is happening. there are products on the market that removed nitrate from your water. The following links will take you to two companies that sell nitrate filter. Before you go out and buy one of these filters, please understand that they are not like any other filter, you can’t just put them on your tank and expect them to do the job, most of them need setting up properly. Some of them can also have an effect on your pH so this is something else that you need to take into account before using one of these filters. Only use these filters if they are absolutely necessary, nine times out of 10, nitrate can be controlled quite easily with regular water changes. http://www.aquatics-online.co.uk/catalogue/nitrate-filters.asp#product490
http://www.aquaripure.com/

I would suggest any newcomer tests as water on a regular basis for the first few weeks after the tank has cycled properly, and especially when the fish are growing. If you’re tank has a properly established biological filter, you shouldn’t have to worry about ammonia or nitrite. On the other hand, the nitrate level will slowly rise day by day until water changes necessary. You will get to the stage where you can work out when water changes are necessary.

Because water changes are so important, it is probably best to pick a day each week when you carry out your water change. I suppose it’s a bit like having a regular appointment,at least it’s not going to get forgotten if you know exactly when you’re doing it.

Remember that Oscars are large messy fish, they produce a lot of waste. You must be prepared to carry out extra tank maintenance if necessary. Oscars are not the sort of fish that tolerate very poor water conditions. They are very susceptible to various kinds of disease so keep your water quality in good condition and you shouldn’t have anything to worry about