Synirr
"No one is a failure unless you try"
Please research before giving advice next time.They seem fine,but they will never live a complete life cycle.Bettas don't live in puddles in the wild.They need moving water.Any fish could live in a bowl without filtration for an amount of time,doesn't mean its healthy as it could be.
I'm not saying its not possible,just not right imo.But I'm not judging you,just trying to point you in a better direction for your fishes sake.
You're right bettas don't live in puddles... at least not all year long. They live in rice paddies, which have VERY STILL WATER. Bettas loathe current, especially the long-finned varieties, and they don't normally encounter strong currents the wild, either. During certain months of the year rice paddies begin to dry up and bettas actually are sometimes trapped in puddles... obviously these aren't ideal living conditions, but it helps explain why they are comfortable living in smaller tanks than most fish. They are fine in still water because they can breathe from the surface and thus don't need surface agitation to stimulate gas exchange. They do not need filters because if you keep them in 1+ gallon containers (larger is better up to about 20 gallons) and keep up on water changes you can keep your water levels perfect for them without one, and I have at least 5 bettas that are 4+ years old to prove it.
Edit: I'd also like to add that I and several other members here actually raise perfectly healthy betta fry without filters. Do you think Thai breeders, who produce some of the best fish in the world, use filters? Many of them raise their fish in big concrete tubs outside.