People breed convict and livebearers all the time for treats for large fish. It's better than convicts breeding so much that you just get sick of it and siphon them into the toilet. Or just let the filter suck them up and not attempt to rear the fry. Let's face it, they breed so much, there's not really anything you can do with the fry after a few months. Let them feed a bigger fish rather than feed the toilet or the filter intake. And it's better for your big fish than feeding them disease riddn malnourished feeder goldfish from the petstore.
Only joking now, but with this logic I should start breeding mice for my cat

Although blood worms will do as well, as he goes nuts over the blood worms for my fish. He licked the whole plate when I left it unattended to defrost
