Hi all, I'm new to this forum and very embarrassed and upset about my recent experiences but really need to move forward.
I have kept a tropical fish community tank for several years and never had as many probems in that whole time, as I have done recently. I decided I wanted to keep oscars and purchased a new 100 gal tank. Set it up with plants, gravel, heater etc and put 3 of my hardiest fish in there in an effort to cycle the new external cannister filter. Everything seemed to be going swimmingly! After a few weeks of partial water changes and the addition of 'cycle' to help things forward, I fell in love with a couple of tiny tigers. I took a sample of my water into the shop (just to confirm my own tests) and came home with the two 1.5" babies. I moved two of the original three fish back to their original tank but left the catfish which I had read would be OK with Oscars. In went the babies who were very active, entertaining and hungry from the very start. I fed them mainly with tiny cichlid pellets, freeze dried tubifex and daphnia, and the occasional frozen bloodworm. They doubled their size almost immediately, then suddenly one developed ick. I treated with Esha Exit (after removing the carbon from the filter) but it just got worse. At the end of the course I decided that maybe the Exit just wasn't strong enough and after 48 hours put the carbon back in for a day, did a partial water change then resumed treatment with Protozin. The ick went but I was left with a bit of mouth fungus and mild finrot. I rang the makers of Protozin, followed their guidelines (watechange, 48 hours carbon etc....) and treated with myxazin.... Everything looked fine for about a week, fins grew back fungus gone .. hungry oscars. Then one started breathing very heavily. I suspected a lack of oxygen but with an aircurtain, plants and a good circulation, this seemed unlikely. All the water tests looked great, I was at a loss. After another two days the breathing was persisting and he stopped eating. I suspected some sort of bacterial/gill fluke problem and decided to treat with a broad range bacterial treatment - this did no good and sadly he died. two days later, the catfish died and the other baby began the same cycle. I tried a 20 min salt bath and further treatment and water changes but it was no good.
Left with a now empty tank and convinced that some nasty critters had taken up residence, over the next two weeks double dosed the treatment. I did several water changes and replaced the carbon. A couple of weeks later I again tested the water and it looked good. The test I use covers nitrite = 0 nitrate=around 25 to 30, PH 7.6 Gh around 6 and KH 12 (the last two may be round the other way) I decided it was time to try again. Stupidly I bought a further 2 baby oscars (about 1" this time). They survived for 3 weeks, no ich, no fungus, no finrot. Then suddenly one started breathing heavily... well you can guess the rest.
The only thing I never tested for was ammonia - my local shop said it was a waste of money and it wouldn't be the problem. I bought the test anyway, and although the reading was small around 0.3, it was still present! I have now added zeolite to my filter and put a shoal of zebra danios in to help cycle the tank some more.
Can anybody tell me whether they think this ammonia has been the problem all along - what would the symptoms of ammonia poisining be? I'm frightened to go through it all again - the danios are fine, the ammonia reading is 0 but I'm still not sure. Are O's delicate when they are that small - were they two young? Please help.




I have the same cannister filter. I wonder outside of the ammonia if it's something up with the cannisters themselves I bought mine about a month ago. I also tried something else as I have several fishtanks. I drained most of the water out of the tank with the problems. And thankfully the fish I have all live in the same water parameters outside of temperature. I raised the temps on my stable tanks a touch to as close to discus temp as I dared and then added water from them all after a battery of tests to make sure nothing was off in those tanks. And added it to my new tank. Almost filling the new tank up (it's a 92 gallon) 55% I then refilled the other tanks which had been drained about 30% each or so. So basically I got all the stabilized water in a tank that's still dealing with a cycle and my old stable tanks got a bit more than normal but their water changes that were due. I tested a few hours later. A bit soon I admit but I was anxious. (and the testing kit was on sale for 50% off so i bought two and they are store level testing kits) And the ammonia had dropped to .25 from 1.0 and the nitrate and nitrite levels were almost perfect and the ph was the same. The discus are no long having black coloring to them and are much perkier and active. Maybe this experience can help you? As yours has made me feel better about my situation.