Betta fish are known for their flowing tails and fins, as beautiful and delicate as lace. Under optimum conditions, bettas can live for two or three years. If you are fortunate enough to have your betta that long, you might at times notice small holes and tears in his fins and tail. There are a number of causes, but thankfully tears are simple to repair and easy to avoid.
Time and Basic Care
Time heals all wounds, and that includes tears in betta fish fins. Betta fin tissue usually heals easily on its own. If you're keeping your betta in a vase or a fish bowl with no filter, you should already be on a weekly water changing schedule. Doing so will reduce the chance of infection if your betta fish tears a fins , and it eliminates the need for any special care or medications. Changing the water is a simple task: Scoop your betta along with enough of his old water out of his bowl into a cup. Dump out the old water and rinse off the rocks, plants and any other decor in the bowl. Place the items back into the bowl when they're clean and fill it with purchased spring water that has been stored in the same room that you keep your betta -- this will assure that the temperature won't shock the fish when you put him back. Pour the cup of water, with your betta in it, into a fish net to drain out the old water, then lower the net into the fresh environment to release the fish.
Purchase water additives at pet stores and add to the clean water each time you change it out. Water additives condition the water, balancing the environment for your betta. Some even contain aloe, which will reduce stress for your fish as well as add a healing element if his fins develop tears.
A Home of His Own
Sometimes it's helpful to take preventative measures to avoid or reduce tearing of your betta's fins. If your fish is sharing a tank with other fish, it's possible that they are nipping at him either playfully or aggressively. There are specific types of fish that you should keep separate from bettas, like bars and tetras. Sometimes goldfish make acceptable tank-mates for a betta, but overall bettas are solitary fish. Yours will be happier and healthier in a tank or bowl of his own.
Remove Sharp Objects
If your betta is already living on his own but you still notice tears in his fins, do a check of the items you have as décor in his tank. His fragile fins might be snagging on the sharp edges of plastic plants, houses or any other artificial item in his environment. If you suspect any of the tank furnishings, remove them from the tank and run a nylon stocking over them. Anything that will rip or snag a nylon will tear a betta's fin. Remove those items you find to be sharp and try to stick with live tank plants, if possible.