Culling (in this case I mean killing) is the unfortunate downside to breeding bettas. There are many different reasons for culling, and each breeder has their own opinions on when to cull and why.
Some breeders use culling as a means of population control or to remove fish that are just not up to scratch. For others, culling otherwise healthy fish for purely cosmetic purposes is all but blasphemy.
I personally only cull fry that are either suffering from physical deformities or are failing to thrive. In the past I let my fry grow out alongside their parents and so only the strongest tended to survive. Those that were slow or weak were picked off pretty quickly by their siblings or were simply out-competed once they became free-swimming.
However, now that I am rearing fry in proper grow-outs, the undersized fry and fry with mobility issues are no longer being culled through predation/competition. This leaves me with a hard decision to make. Do I cater to these fry and hope that they get better, or do I cull them and focus my attention on the strongest of the group?
At the moment I seem to be facing a recurring battle with ich in most of my grow-outs. Therefore, I am going to cull all but the biggest and healthiest of the fry. I figure they have the best chances of survival through the next several weeks of treatment, and I am concerned the weaker runts may be more susceptible to becoming re-infected.
Making the decision to cull is never pleasant, but I feel that it is part and parcel of being a responsible breeder. In the wild generally only the strongest fish would survive to pass on their genes, and so it doesn't make sense to me to pass on inferior fish that may be allowed to breed once in the hands of their new owners.
If we are going to conserve these rarer species, we must not do them the disservice of introducing inferior genetics into an already limited gene pool. That to me, is not in keeping with the best interests of these fish.
Hailing from Melbourne, Australia, I currently keep and breed a number of species from the coccina complex.