I have the same problem in my 150g Malawi cichlid tank. Only I have so much incricate rockwork and hiding spots, it really is virtually impossible to pull any fish out without dismantling all the decor in the tank. I'm essentially just letting them grow out, and dreading the day a few months down the road when I will have to do that.
I saw your title about fishie condoms, and got excited that someone may know how to sterilize a tank of fish, lol