Hello there!!
Firstly, I must say that I have been reading some of the wonderful adivise on this forum and site... most helpful!!

I need to ask for a little bit of help right now, and I do apologise if I am asking something that has already been answered. I am searching through the answers to questions and articles on this site, and approx. 6 others, and am coming up a little lost in finding what I need.
My partner has built me a new tank, dimensions 150 X 60 X 75 cm. (630 litre capacity) which I am currently in the process of setting up and cycling. I also have a 2ft tank with a 55 litre capacity, which has previously been used for breeding guppies and betta’s. Filtration is an AquaOne 101F Power Liquid Filter 400l/hr with the attachment to have the spray sit slightly above the water for agitation and oxygen, as well as one airstone for added oxygen. The tank parameters are as follows:
PH: 6.6
GH: 10 dH (approx. 175 ppm)
AM: 0 – 0.25 ppm. (have treated for white spot with methylene blue, tinges the test result ever so slightly and makes it hard to determine... I believe this would be closer to 0 due to water changes as explained in a moment)
Unfortunately, I have run out of reagants for both my Nitrite and Nitrate test kits, and am heading down to get the water tested at my LFS as well as purchase new ones, just wanted to shoot this off quickly!! I do however maintain my water changes religiously, monitor food waste and adjust feeding accordingly to minimise any waste and contamination in the water, I also observe my fish closely and so far have been travelling wonderfully, last recorded levels were nitrites 0 ppm and nitrates 0.25 ppm.
Occupants consisted of 3 x adult guppies, tank had been running for approx 12 months.
Nothing had changed in the aquarium other than the addition of an airstone and new plant. The plant I am uncertain about and has since been removed – it was artificial, and made out of more like a silk/fabric. I purchased it from my LFS and claimed to be ‘approved’ on all packaging etc. However, i’d rather be safe and have taken this out just incase it was possibly breaking down or throwing off some kind of toxin.
The Oscars were added to this tank for the time being until their home has been sufficiently cycled which should only be another 4 weeks at the most. I figured if they eat the guppies then so be it, they are intended as breeders for feeder fish anyway.

I have recently (one week) purchased two juvenile Oscars. One tiger and one red. Both were approx. One inch at the time of purchase, were strong, healthy and paired up at the shop. I bought one to begin with, but ‘she’ (as i’ve dubbed her, when she’s larger i’m almost certain it will actually be male judging by behaviour, but right now i’m calling her a girl) was rather sulky and unhappy, so the following morning I went back and purchased her buddy, who was behaving the same way in the shop. However, when I got him home, approx. 5 hours after realease his breathing became a little laboured and he was quite lethargic, hanging around under the heater. The Tiger O had claimed herself a cave and would head over to him and it appeared to ‘snuggle’. Laying close, nudging him up and forward, quite friendly appearing, no tail shaking, fins not extended, no nips. He seemed to perk up after another hour or so and they were happily swimming around and cosying up under a rock. I put his earlier behaviour down to stress and settling in, gave them some blood worms and both were eating.

The next morning, I found one guppy dead and a little battered, figuring the Os had just ganged up on them and killed one. Nothing out of the ordinary for them. The Red O was again under the heater/filter and breathing heavily and more rapidly than the night before. I checked the water parameters and came up with the same result. The remaining 2 guppies and the other Oscar were behaving normally. A few hours later, he was displaying signs of weakness, still laboured breathing, and leaning to one side or the other, but was able to still swim around. The tiger O began to ignore him at this stage. I checked the water again, all fine. I decided to do a 25% change even though it wasn’t due incase I was experiencing a nitrite/nitrate spike – no ammonia though. It seemed to have no effect on him. I also noticed a little bit of white spot appearing on his fins and on one of the guppies, and treated with 10ml methylene blue in 55 litres of water (dosage is 0.25 ml which works out as 12.5 ml – i always slightly underdose with this just to be safer). Raised the temperature to 29C and the next morning the visible signs were gone from both fish. Treated again with a slighter lesser dose (approx 8 ml) 3 days later. However, prior to redosing, I found that the pH had swung dramatically toward alkaline, approx 8.3 I have never experienced a swing as dramatic as this or in this direction. I corrected and it has remained stable again at around 6.8.

The Oscar continued downhill with his breathing becoming extremely laboured and fast. He stopped eating and became rather agitated. Constantly cranky and displaying aggressive signs, tail shaking and charging anything/anyone (human or fish) who would happen near his corner. At this point my Tiger O became aggressive and would attack and pick on him. He ended up with some wounds an I separated the two within the tank to give him a chance of recovery. I completed another 50% water change at this point. Approx 3 days after this began and he stopped eating, he weakened to the point he became caught up in the current and had trouble staying upright. He would spin around and when he eventually died late last night, his mouth was gaping wide open. I also found the guppy displaying white spot symptoms to do the same thing, and died a little while before the Oscar. Mouth open. I had read some things about whirling disease before, but thought that it primarily affected cold water fishes especially salmonoids... I have been unsuccessful finding information pertaining to it in Oscars and how to treat. Is this even a possibility???????


This morning, I have found my tiger O beginning to breathe slightly heavier than normal. I have immediately upon finding this completed ANOTHER 30% water change, and she appears to have eased a little. She is still highly active and eating – however not quite as piggy as normal. I have only had her for a week, but she is already taking food from my hand and coming to greet me when I approach the tank. This morning she was giving me a look as if to say ‘im not well.. help me! Make it better” I felt so horrible. The remaining guppy is breathing quite fast but like the O is very active and eating also. I know it sounds like something terrible is going on in my water – but I just can’t work it out!!!!! Everything appears fine. I am double checking with my LFS once I have posted this, and will update shortly what results they turn up. Perhaps my tests are faulty? ?

Finally, she appeared ever so slightly bloated upon turning the lights on this morning, and then about an hour later after i had completed the water change when I checked her, she had done a HUGE poop and looks ever so slightly emaciated now. This is making me think of internal parasites now, and i have had a look but so many different things seem possible, I think I really need a little bit of more experienced and expert advice to help me sift through the masses of information. Please help me work out what is going on and how to treat this. I am planning to continue daily (up to twice daily if necessary) water changes until I can figure out how to treat this. My thoughts are that if there is a toxin in there, perhaps from the plant i’ve removed (??) this will lower the concentration, and the same for if i’m experience Na3 & 4 spikes... I really don’t want to lose my girl, i’ve grown so attached already.

Thank you so much in advance for your time in replying!
Cas

First off, Hi and welcome to the site!

Secondly, We need exact readings for Ammonia, Nitrite, Nitrate, PH, and Temp...

Make sure when you buy the new tests that you get the LIQUID test kit, and NOT the strips...

Hello Again Thank you for your reply! I was about to update with a summary of the water parameters and the results from my local stores when I noticed your reply. Apparently I have email notifications off...

I use API tests in the liquid forms already. They are all only approx 6 months old, I just thought perhaps something might have been wrong there. My results were:

Hardness: 10 dH or 175 ppm. >> I know they like soft water, but I find slightly harder helps to stablisise the pH and prevent sudden changes. To all of my research and experience they happily live within 5 - 20 dH and therefore i tend to keep it between 150-180 depending on how the individual fish appears to prefer.
Nitrite: 0ppm
Nitrate: 0ppm
PH: 6.8
Ammonia: 0ppm. >>> It appeared after treatment with methylene blue to be somewhere between 0ppm and 0.25ppm. After cycling out of the tank in the few days since treatment the test has returned to 0ppm.
Temp: 26 (78)


The remaining Tiger O is happy, active and breathing mostly normal with only small bursts of the rapid/laboured breathing. Usually this is following a burst of activity and she soon returns to normal, so I am beginning to think that perhaps she is just being typically juvenile and 'unfit' to an extent, tiring easily. However, with the track record of the past few days I am unwilling to accept this as an explanation. Do you have any thoughts about this?

your test results are certainly wrong. I am 100% certain of that. met blue will knock out all the bacteria in your filter. your cycle will be lost. you will have high ammonia/nitrites no matter what your test read. with a small tank I would do 50% water changes daily maybe even more.it may be better to do small amounts throughout the day. your fish are suffering ammonia poisoning/oxygen depletion. this together with high temp of 29(use 27c) will reduce oxygen in the tank.

I actually got the same results at two local stores this afternoon when I had the water tested. The temp is also at 26, not 29 now and all the meth blue has been cycled out and cleared up. I have also completed a 50% water change 4 days ago, 25% the following morning, 30% that night due to the sypmtoms the fish were displaying. At all times the testing has been consistant from my end, and I had that confirmed today with two stores testing my water, one using AquaOne testing solutions, the other API.
I have completed a 25% water change each day and monitored all levels closely for the past 4 days.

I initially thought the same as you, ammonia and depleted oxygen levels, however my filtration turns over the water capacity more than adequately (55 lt with a 400l/hr powerhead) as well as an airstone and the surface is agitated by a spray connection. I have live plants as well as artificial.
I am beginning to think that this may have something to do with the new plant I added. I bought it from a local aquarium store, however it was silk type plant as opposed to the normal plastic type. It was all 'approved', 'safe' and 'tested'... however I still feel that being the only new addition other than the airstone, this may have thrown off some kind of toxin or chemical which the fish have reacted to??

My other thought is perhaps there is something happening with our local water supply. I know we have quite a high concentration of chlorine, and a pH of approx. 8, however I use Wardley's TriStart (at the double recommended dosage as stated due to our high chlorine levels) as well as AquaOne Armour Coat to neutralise chlorine, chloramine and any metals. However, one local store addmitted to similar problems with both their personal tanks and the store stocks, beleiving it may also be the local water?? I am wondering the benefits of perhaps using bottled water or even boiling and cooling water in preparationg for changes? Does anyone see this perhaps helping? My theory is, if it DOES happen to have to do with water supply, then I would only be doing furhter harm by continuing this regime?

Please do not get me wrong, I understand the consequenses of Meth Blue. I have been breeding fighters, gouramis, guppies, tetras, and mostly smaller tropicals for quite some time and using this as a treatment for ich, open wounds, and a variety of fungal infections. However, I have learnt over the years that adjusting dosages to a little under recommendation and not removing carbon from the filtration systems helps to decrease the effects to the biological filtration system. Yes it does indeed take longer to treat ailments in fishes, however I find that the general stability of the ecosystem to be of greater importance to myself. I also rely somewhat on the fact that I am currently a returning university student and spend a lot of time studying nearby my tanks and observing. I often catch things in very early stages and do have a separate hospital tank to treat.

Perhaps even the Red O was carrying a disease from my LFS and unfortunately the smaller occupants were more susceptible? I am honestly at a loss...

i agree with marcus... something is wrong with the data.... its
either you did clean your filter with tap water or you lost your
beneficial bacteria even if you make mild dosage....losing fishes
in a row means something is wrongs.... i have to re-read your long post
to find were it went wrong.... i will post later what ever i find....

look at it this way. if the fish where sick they would not die so close together, its not that common for sick fish to die one after another. maybe a few days or wk apart.

another issue is I have not seen filters survive met blue dosing. it may also kill your live plants off, so if they start to look poor, its the met blue. it is however a very good treatment, but I would use it in a small empty tank with good circulation of water. maybe the met blue is throwing off the tests? some kits give wrong results with some meds. your carbon isn't going to absorb a full dose of met blue, before the filters affected by it.

lastly you mention your PH change. maybe that was down to a wrong reading(again met blue related)and not on your part. if the readings where wrong you changed/dropped the PH. this could be another issue. Are you certain met blue does not give false readings with your test kit?