yep, if you drag a pair of panty hose over them and it snags it can tear a bettas fins, males are realy more of a prob with it, my female can do with some, i keep a 10 gal with at least 4 females, that way no one fish gets picked on too much, a 5 gal is small and only good for 2 to 3 fish 4 streching it, but you will get a ton of fighting ,, even females can go for the kill!! try to get spawn sisters as them seem to get on the best from my experence, and remember all bettas are different and some just wont stand to have any other fish in their tank, so might be good to have a emergency spot set up if you get females from diff locals and they wont calm down after a day or two.