Thanks for all the replies. Its been interesting reading.
The dimensions of the tank are approx 50" long by 18" wide.
Im guessing its too small for an adult oscar judging by the comments. Would it be ok for a gulper cat?
It is a tank I inherited from a friend that is currently overstocked and Im hoping to sell off what is in there and go for some sort of specimen fish.
That's a better footprint than many people keep Oscars in, if you're set on it you can do it; the real question is down to whether you're prepared to do large water changes, they produce a ridiculous amount of nitrates

