i have a 3" red zebra, kenyii, yellow lab and a 2" acei. i have had them all since they were very small but for some reason the zebra and kenyii have started to beat up on the acei and when the zebra gets tired of that he chases the lab. i knew when i got the acei that they are not as aggresive and i would have to keep a close eye and now i need to do something. it's only nipping at fins and a little mouthing so far. any suggestions on how to make this a happy fmaily?