I'm on my 4th Green Terror in the last 3 years, this male looks great has grown pretty quickly and is quite a hog. He's about 7" and is probably a little over a year old. He is in a 270 gallon tank and is about the largest fish in the tank, and most dominant outside of a Jack Demspsey, but they usually don't quarrel. I feed him a variety of different pellets, occasional krill and river shrimp freeze and black worms freeze dried, and some lettuce. He looks fine, but he has stopped eating/going after food for the last 3 days. I'm worried, because I've lost 3 others that attained his size and for whatever reason something happened to each one of them. One had a swim bladder issue, another I couldn't determine. No other fish in the aquarium are showing any signs of illness. What should I do, quarantine or give him a few more days and see what happens?