Bettas lay from 60 - 500 eggs and if ur not careful all of them could dye from the female eating them! They won't all live , either way. So the most reasonable amount would be...............5 - 20. That is still alot but i have fry in my bettas bubble nest , and i see tons of fry so my guess is theres about 50 living in there but , they might dye while im sleeping or away from home because they might come out of the bubble nest [when there old anough] , [ which is about 2 weeks] and the male might eat them , i might end up with 0 out of 500 , so u never know what might happen