Ya I have had a lot of tanks and fish, and none even came close the this fish. I don't know what it was. This fish caused me more grief than any other. When I got rid of all my tanks and fish I only kept him and his tank.
This fish kept my 150 gallon bare with him only for about 3 years. Killed probably over $300 worth of fish easily. After I put him in prison in the 90 gallon he learned a trick to get me to feed him. He would swim near the surface and then bolt downwards flapping his fin out of the water like whale. Of course this would put about 5 gallons of water on my hardwood floors, my cat soaking wet and my fiance chasing me with a butcher knife.
Yet after all that I could never get rid of him