My 9" N. polystigma stopped eating all of the sudden. He usually eats everything I put in the tank. He is the only fish that stopped eating. Only thing that has changed in the tank is my 9" male N. Venustus has become pretty "interested" in the female venustus and has become aggressive towards every fish in the tank. Befor this, the polystigma was the dominant fish in the tank. Not any more. Do you think that it could be stress that stopped him from eating? I've tried everything from flakes, pellets, bloodworms, crickets even guppies. He doesn't go after any of it. Any help would be great. Thanks