Last year I attempted to breed 6 males all two year olds and in the 700-1000gram range and only two out of the six would breed The others showed zero interest.
This year everything is breeding, even my 6 month old butter male. Who knows? The animals I'd say.
Jas you mentioned BT he's got 6 or 7 07' males all breeding!! All I need to know is what you guys put in the water?