You asked about whether females can color up like males. The answer is yes and no, basically it depends on the species - sorry that isn't exactly helpful. But, the real answer is to vent them. I have never had an all-male tank, just not what I like, but if I was going to set one up I would vent every fish to minimize the chance of introducing a female.
Also, I am going to assume that you don't have species groups in your tank, therefore the fry are hybrids. I don't want to start a whole argument about whether hybrids are good or bad, but please don't give them to your LFS. Hybrids are regularly sold as fish that they are not, which can be very upsetting when someone is trying to set up a species only tank (only one species in the tank). If you sell or give the hybrid fry to your LFS, they will likely try to ID them and sell them with a false/wrong ID - especially a place like P_co or P_smart (the workers don't generally have much knowledge of the fish they sell). If you like them, keep them - just please don't allow them to be sold as something they are not.
Also, I am going to assume that you don't have species groups in your tank, therefore the fry are hybrids. I don't want to start a whole argument about whether hybrids are good or bad, but please don't give them to your LFS. Hybrids are regularly sold as fish that they are not, which can be very upsetting when someone is trying to set up a species only tank (only one species in the tank). If you sell or give the hybrid fry to your LFS, they will likely try to ID them and sell them with a false/wrong ID - especially a place like P_co or P_smart (the workers don't generally have much knowledge of the fish they sell). If you like them, keep them - just please don't allow them to be sold as something they are not.
