I think people underestimate the scale and speed of the problem.
When I had endlers there were only males for sale in the color morph I wanted (in other words, the breeder was protecting their line by not offering females), but more frequently I only see live-bearers sold in pairs if you are after particular colors. I'm not sure how people manage this if they aren't breeding for profit. I assume they quietly cull a lot of fish? It's definitely a math issue.
Yes, they cull like mad, all breeders of fish, cull, heavily, a torch and a magnifying lens and, yes, a lack of sentimentality, not for me I admit. Only deformed or ill fish ever get the 'chop' from me. Instant death. Tragically, in almost all fields of animal breeding this process occurs, think of male cattle or male chickens.
Having said that, when people get over sentimental about Mother Nature, I think of bacteria, waiting, for an opportunity to kill us, prematurely, after all, until the 20th century, TB, Cholera, Diphtheria took lots of us, quite quickly, in our younger years. But now, cheerful thought, most of us get the chance to experience the other side of Mother Nature, slow death, later in life, from what we have inherited from our parents and grandparents, with a bit of time related mutation. Thus in the affluent part of the world, we die from our own DNA mutating or other complex biochemical changes, cancer, heart disease, strokes and dementia. I suppose, better than dying young from polluted water.
A few tiger barbs doing what comes naturally, seems to me, in anything other than a small bare tank, to be as close to natural and humane as it gets.
