How many bettas are you keeping in a single tank? Males and females should never be kept together unless they have been properly conditioned to breed; he should be moved to his own tank.
The best treatment for torn fins is clean water, so stay on top of water changes while he heals and, depending on the size of the tank, whether it is cycled, etc., you may want to add an extra water change to your schedule as he heals. A small amount of aquarium salt can also be used to help prevent infection, but do not use it if there are tankmates that may be harmed by salt (frogs, some catfish, etc.) and do not use for more than 7--10 days.
Last edited by LolaQuigs; 02-25-2015 at 02:32 PM.