Ok, I have a 40 gallon aquarium for now (getting a 75 in a few months. I bought a 4 inch oscar on saturday to put in my 40 gallon tank. Got him home he was fine for awhile. On sunday he was laying at the bottom leaning on his side a bit and will not eat. On monday morning I got up and he was breathing rapily, gills going in and out and mouth opening and closing alot. So the first thing i did is test my water again, my Nitrite was 0 ppm, Nitrate 0 ppm, pH 6.0, ammonia was slightly above 0 ppm, it didnt even register to the next level on my testing card. I know your thinking how is the water perfect, well i didnt have anything in there but rock and fake plants for a month. Its tuesday i have tried flakes and feeders and he wont eat a thing. After testing the water again and everything was fine. he was still breathing rapidly and so i added a pump thing that makes bubbles to give him more oxygen and he is STILL DOING IT! WHAT IS WRONG WITH THIS FISH!!!!!!!?!?!?!?!?!

welcome to oscarfishlover

After reading your post, it does rather sound like you put the fish in the tank before cycling it. I think the reason why your fish is breathing heavily is I suspect because there are toxins present. what kind of filtration are you using? how is the water entering the tank, is it creating bubbles? You say you have put a pump in the tank, is this also creating surface agitation to the extent that there are many bubbles being produced? I just want to determine whether the oxygen levels out okay, lack of oxygen will make an Oscar behave just like what yours is doing.

Okay, what type of tests have you got, could you give us the exact type please? How long after the fish going into the tank did you test the water?

Could you test the water again, please make sure you are doing absolutely correctly, it is absolutely vital we know that you have done the ammonia and nitrite tests properly. Nitrate isn't so important that you say you've got a reading of zero. Depending on how long the Oscar's been in there, this will indicate that the tank is not cycled.

Sorry for all the questions, it is very important that we know exactly what you have been doing:)

its a top fin aquarium. water is filled to the top where it drains back in. should i take some water out to make it have more bubbles?
oh and its a master test kit just like the one in the picture u have on this site

how long have you had the tank set up?

a couple years but i completely cleaned it out 4 weeks ago.

the hole laying on his side and not eating could just be him sulking..

when i first bought mine he did not eat for 3 days and he just hid in a little tunnel...

it might take a day or 2 for the oxygen to build up in your tank, just make sure you keep the pump on quite alot if not all the time..

hope this helps and keep us posted

it takes around six weeks to cycle a tank, unless you're doing a fish less cycle, have you cycled it?

labored and heavy breathing, a rapid gill movement is a sign of trouble, a fish should not do it. It sounds as if you are oxygenating the tank okay. is any way of taking some video footage? You can upload photo bucket. Rick is correct, Oscars are sulkers and a fish will breathe heavily if it is stressed. However I wouldn't expect this kind of behavior to go one for too long if water conditions are okay.

So if you can tell us if you filled the tank up with water, left it for four weeks, and got your fish