I have 19 Tilapia in a 55 gallon system that I've had since fingerlings. That was 6 weeks ago. Now some of them are getting larger, but not all of them. Some are over two inches while some are about an inch. Perhaps the smaller ones are females? These were mixed sexes intentionally.
Also, one fish seems to be a loner, while the others stay fairly close to one another (usually near the bottom of the tank).
Should I be concerned about this fishy behavior?
Thanks as always Fred the fishman