Fin rot or tail biting?

[WXchick7]

Ok, I don't have a good enough eye to know the difference between fin rot or tail biting...so I'd like y'all's opinions. I think it's tail biting...his tail has gotten more and more ragged in the last month and this is definitely the worst it's been... Thanks! (Sorry the image is so large...)

[Capricorn]

I want to guess tail biting, but I'm not sure.

Either way, the best way to help is to keep his water clean. (:

[WXchick7]

Thanks...yeah I'll be cleaning the tank again on Friday.

[Adastra]

Tail biting. Just keep the water as clean as possible and carefully re-evaluate different aspects his environment for possible sources of stress, i.e. water quality, temperature fluctuations, water parameter fluctuations, proximity to other bettas, proximity to reflection, lack of hiding places, strong current, etc. If you get to the root of the problem, he should stop tail biting. It may not be a trigger you expect, though. One of my biters didn't like being in total darkness at night, so once I got a dim night light he stopped. Another one didn't like a certain piece of decor in his tank--once I removed it, he stopped biting. You just have to go through a process of elimination until you figure out his trigger.