Oscar Sick

Hello. I have a 2-3in tiger oscar that I had just bought from a pet store, it looked healthy at the store, but after coming back and putting it in a 55 gallon tank, after one day the oscars top half started to change colors , he still eats and is active, and i treated him with coppersafe thinking it was a parasite. his top half turned grey and his fins look a bit damaged and he sometimes tilts a little bit sideways when he swims (btw i dont think its fin rot since i don't think fin rot changes the color of a fish, unless he has fin rot and something else) .. he lives with 2 other fish that the place i bought from recommended as tank mates, they seem to be fine and only fight a little bit. Could it be a fungus or just stress from the other fish.

[dstrong]

try treating your tank once a week with stress coat.  when i worked in the fish dept of a store and we got fish deliveries, i would treat the tanks before the new fish arrived with the stress coat and acquarium salt.  a lot of our came in sick cause they had such a travel.  we went from a lot of dead fish returns to as little as 7 a week.  it really helped.  also, keep a check of your ph and alkaline levels.