Hi I have a 5" (approx) Oscar over the the past week he has been sulking sitting on the bottom and breathing rapidly (mouth opening and closing constantly)He will come out of it and swim about but then goes back to the bottom, He did go off his food but never stopped eating completly at the moment he is eating fine. All the other fish (silver dollars and sharks and a plec) are fine the water is as it always is nitrate 25 nitrite 0 ph 6.8 we have hard water but the water at the shop is the same as ours. I do weekly water changes and he gets a variety of food cichlid pellets, blood worm frozen cichlid meat the ocasional bit of liver and other pellet food he greeds from the other fish. W e have had him about 3 months. Any help will be gratefully apreciated.