I have a 10gal planted tank. I have Red Cherry Shrimp and I had 4 male Fancy Guppies. One disappeared. I looked everywhere. In the tank and outside and he was there one night and not there the next evening. Anyway, everyone used to get along well but now two of them are picking on the third. They never did this (that I saw) when there were four. What do I do. I distract them with food but I don't want to foul my tank.