Recently one of the snails in my aquarium died, under a rock so I didn't know it.. Then one of my oscars rapidly died. And after transporting my other oscar and a catfish to a temporary tank and doing a full water change, now my last oscar I believe is also dying. Here are his/her symptoms: Body is slightly crooked to one side. Sometimes swims normally, but usually in a circular motion, and lays on the bottom of the tank crooked. Is there anything I can do for it? It's a young one, so it's not from old age..

when you say crooked to one side, would you also describe it as looking like a curvature of the spine? If this is the case, I think your fish is probably beyond help since this problem can be caused by a parasite, or tuberculosis. However, the best thing you could do to get a reliable diagnosis is to visit a professional veterinarian

That certainly isnt one of the usual problems you get. The only time i have seen fish with curved or deformed spines is when they get old

Water changes of above 50% are not recommended unless it is an emergency as the fish can become shocked. If you do need to do very large water changes then you should age the water. Black water tonic and Ph up/down should be used to age and match the water to the tank water

The snail probably died either from poor water or because an oscar grabbed it and killed it. Snails are not good tank mates for oscars as they are a natural food for oscars

I have just phoned my friend who used to have a fish shop and has a very good knowledge of tropical fish.

Fish usually get tuberculosis when they are kept in appalling conditions and then some fish more likely than others

She also says that curved spines can be caused by the fish being poisoned. Over treating with medications without any water changes can be a cause. Another possibility is from poor water quality. If you dont do enough water changes or massively overfeed you eventually end up with ammonia in the water and this poisons the fish

Do you test your water for ammonia, nitrite and nitrate. How big is the tank and how often do you do water changes and what percentage do you do change. How much do you feed and how often, do you remove any excess food

Unfortunately there is no cure once the spine has curved. Euthanasia is recommended.