Growing on fish

[mummymonkey]

Both my juvenile N. anomala and M. ramirezi have spawned in their growing on tanks. Obviously this is a major PITA. Any tips to prevent this? I don't have a huge number of tanks and space is limited. I was hoping to grow on the Rams to a decent size. The Anomala I can seperate out into sexes, it's difficult with young Rams.

Also what is a reasonable number of M. altispinosa fry to grow on in a 36" x 12" x 12" tank. I have over a hundred at 3 weeks old, still with their parents.