why do you need to keep them from breeding? is your work just a normal job or is it fish related? id say just leave em as is, if they breed you can euthenize the young , or who knows maybe the parents will eat them
long story but we have to make sure eggs dont get into the watercourses round here. We have a licence to keep them but have never sexed them and i thought we should do it to see what they are. We have all the precautions needed to make sure that eggs dont get out but for my interest i wanted to see what sex they are.