i have a 29 gallon tank, it contains 3 angel fish, about 3inches each, 4 glofish, about 1 inch each, 1 rainbow shark about 4 inches, and 2 siamese algae eaters, each about 2 inches, everything was fine, suddendly the rainbow shark has become very aggressive, chasing all the smaller fish, it has killed 1 of algae eaters, there is plenty of room in the tank, id like to keep the rainbow but not if hes going to stress out all the other fish, any suggestions would be appreciated.

Hmmmmm.......That's a pretty good sized rainbow shark.

Maybe you could poke one of it's eyes out and bring it down a bit in the pecking order.

Just kidding!

IMO I think you may need to take it back to the store. Most aquarium stores will take fish back, as long as you don't expect any money or credit for it.

I can't think of anything else. Maybe someone else has the answer.

I've had many sharks. You need to take the rainbow shark back to the store or get a larger tank. He's being aggressive because he doesn't have enough room. Rainbow sharks are highly territorial and need more space than the typical one inch per gallon. They will claim a space in the tank and generally leave everyone alone if no one invades their space, but 29 gallons, particularly with the number of fish you have, is too small for your shark to claim a territory. I've had numerous sharks with success in community aquariums, but they need a large tank, with a minimal number of tank mates. Also, he probably killed the SAE because you can't keep other fish with similar body shape or coloration as the rainbow shark.

Z