I have got a 75 gal. tank to use as a breeding/nursery tank. I want to move one lucky guy and three girls into the tank for an orgy of sorts. I have 23 Tilapia in my main 150 gal. tank. I picked the biggest fish for my main man. This was easy as the boys supposedly grow bigger and faster than the girls. After a few tries I got the big guy and inspected him. Best I could tell just the single tiny hole and no half moon slot. After many tries looking for girls, I know I have at least one because of past babies, I have yet to get a partner caught.

My question is, with all this catching and releasing, probably some of them twice, how stressed am I making the fish? The last thing I want to do is kill them trying to separate some. The only way to sort them is to catch and inspect but they all look alike before you catch them. Any ideas and advice?