I had a large feeder Goldfish that had been eluding my turtle for a long time so I put him in a 30 gal
by himself, and played with him alot using a laser pointer. After a while I started to wonder if he had a predator instinct so I put some smaller feeders in with him and
! unfortunately later a young Green Terror was added and it got sick of being bullied by the Goldfish after about two months ending in a fight to the death with the Goldfish losing, but not by much.