Sorry about the Betta...
I had a mishap with my fry, mostly a time thing (the joys of parenthood, full time job, owning your own business, and running a small menagerie), but I started loosing them for some reason (assumably bacterial, because it happened after I jarred them up)... So I put them in the water garden to grow and they definitely took off after I put them out there (spread among the various 15 gal water garden pots with water hyacinth, daphnia, and scuds... And mosquito larva) And their dad: my spectacular import decided to randomly eat a huge chunk of his own tail... Mishaps.
...fortunately it is growing back, but that was heartbreaking.
Pygmy Cory barbels grow back pretty quick once they get happy. How long have you had them? They are notoriously "delicate" from everything I have heard and experienced... Once settled in and happy they are great, but they take a good long time to "settle in" and "get comfortable": people say after shipping, don't be surprised if they randomly die in the first month, and they don't even really like switching tanks. One of my LFS friends won't carry them because she spreads her Corys out among her walls of tanks (they will be in one tanks for a few days, then get moved to another to "clean up") and she complained that they jus randomly kick the bucket.
I've had my colony (started with 10... It's closer to 50 now... Not counting the ones I've sold or given away to friends) for 3 years... They breed like mad on water change days, and I keep 15 or so in my 10g nursery tank and they are the best in that tank... I've never seen them bother fry (even their own... Which are tiny) in fact I blamed my Betta troubles on removing the fry from the Pygmy Corys.
But they really are super social... When you can, I'd pick up a few more. They are super cheerful little busybodies.