I have 5 Serpae Tetra , 5 Neon tetra and 4 Gold twin bar platy. The Serpae tetras are nipping at the neon and twin bar platy's fins. Is there anything I can do to stop this? Will the fins grow back? I was thinking about getting more Neons and twin bar platy's to see if this would stop the nipping. I have a 26 gallon tank.