I had the same issue with a bicolor, turned out to be a total bastard!!! Killlef Evert fish I tried adding after him, constantly harrasssing everyone that was there before him. Luckily I was able to catch em fairly easy, after I caught him I had the fish net sitting on top of the tank with the net inside the water, and in the blink of an eye he jumped out and committed suicide. Never saw him again, probably glad too. I'm sure it would of been a lot Hardee to catch em a second time