Infusoria and boiled egg yolk are really only recomended for the first week at most, then you need to move them up to BBS and microworms or vinegar eels. My research so far has indicated you can't just feed a diet of only vinegar eels or just microworms, as they are deficient in needed nutrients and vitamins and you will end up starving your bettas to death even when they have full bellies. BBS is the recomended food once they are big enough for it, as the freshy hatched brine shrimp are one of the more complete foods out there for fry. Please be sure you start your culture(s) BEFORE you spawn your betta. If you do it after, or once the fry have hatched, it will be too late and the fry will starve to death before you have the right food to feed them.
Oh, and the topic of mosquitoes. Feed mosquito larvae, and not the mosquitoes themselves. The larvae are MUCH easier to harvest, and much easier to feed to bettas. The larvae can be harvested at various times in various sizes, and they are much closer to a baby betta's mouth size. They are also less likely to bite you xD
What size is your spawn tank? What about your heater? Betta fry especially need heated water, they are very sensitive at that size. It must be stable at 80 degrees, no less. What are you doing about lighting? What about your filtration system? Are you going to have a filter in your tank? Do you know how often you are going to need to clean the tank? How are you going to clean the tank without sucking up the fry? Do you have all the grow out jars yet?
You've got the basic idea so far, but there's a few more details I think you need to work out before you make a go for it. You're getting there though.
Last edited by Nataku; 04-03-2009 at 08:43 PM.