Scavengers dying in tank

Question
I have an aquarium that is divided into two sections i have 3 Oscars in one section and 4 iridescent sharks in the other - one about 6 inches and the others about 2 inches.  i also have two scavengers in each section.  The scavengers died after one week and the small sharks died also but the larger shark and the Oscars are doing fine. can you tell me what is the problem

Answer
Hi there,
I would suspect water quality problems. I'd test your water for ammonia, nitrite and nitrate if possible and do some large water changes just in case.

Oscars and sharks are very high polluting species and can dirty their aquarium very quickly. So its easy for pollution problems to arise.

I hope all is well!
Karen~