Depends on which fins are cut and where...If they're cut at the base where the bone comes out, they might not. No fish should be kept with crawdads. The crawdads will either try to eat your fish (and you'll have wounded or dead fish) or they'll be eaten by your fish.
There are some pretty decent fin regrowth meds ouit there. Bettamax or soemthing like that seemsed to help my betta when he had ripped fins. Of course he then went and tore off one of his pectoral fins and it has never grown back. He is still doing well though.
shame on the crawfish!
if your betta is old (maybe older than a year and a half), it might never grow back, but you should still put him in some bettamax-or i like polyaqua too if you dont want the water to be green (and if you can find it)
i hope he gets better!
No shame on the crawfish, it was doing what it was supposed to do.
I'm sure I've mentioned the story ad nausem of the little crawfish I saved from a Hispanic grocery (legally of course, I don't steal). He was big and he could easily eat most of the fish I've ever kept. Not to mention those claws...
Bettamax is most defintely what you want. The fins will never look completely right, if they do grow back correctly (if the rays were cut, they won't), but he should be okay.
just about all of my bettas with nipped fins from breeding grew back perfectly. but they were all under 6 months of age. there is hope.
i suggested polyaqua because some people dont want to turn their water green, or add it if there are other tank inhabitants. (although you should seperate the betta while healing) it works just as well for nursing rips and tears.