Bettas are known for their long, flowing fins, fanning regally as they swim. Unfortunately, tail biting can be detrimental to these spectacular features, resulting in ragged, broken edges. At times, complete sections can end up missing. While tail biting is not entirely understood, there are a few ways to troubleshoot the issue.
Before assuming the problem is, indeed, tail biting, eliminate any environmental issues that may be the cause. Check the quality of water in the tank to ensure it is up to par. Then, examine the environment for any items that may result in injury. This can include pointy plants or rocks with sharp edges as well as filters that provide a strong suction. If your betta does not live alone, observe to rule out injury caused by an aggressive tank mate.
If environmental issues are not the problem, then your betta is the culprit. Shipping conditions and handling along with transitioning to a new tank can result in high levels of trauma for a betta and the tail biting can be a result of these stressful situations. If there are other aggressive fish nearby, bettas may bite their own tails out of frustration of not being able to get to the other fish. Feed your betta at regular times to ensure hunger is not at play. Bright lights can increase aggression, stress levels, and confusion in bettas while increasing their sense of exposure and vulnerability. Dim the lighting for a more soothing environment. Add in a variety of plants and caves as well as a few community fish to reduce possible boredom.
While identifying the cause for tail biting in your betta, it is vital that you maintain a clean tank to offset the chance of infections. You can also add medicinal treatments to the water to reduce bacteria, prevent additional damage to the fin, and to support new growth.