there's probably 35-38 F1's adullts that i grew up from fry from 2 diff. sources. if i let them spit in the tank there are no survivors, no matter how much cover i provided. i've sold the fry since i started stripping them, so the answer is no, i haven't mixed any fry back into the tank. they're currently in a 6' 110g -- previouosly had them in a 180g, but needed that tank for a group of kitumba fronts that needed the bigger tank.