Whats wrong with him?

[Betta_man]

My betta has a badly torn fin, He seems fine apart from a large chunk missing from his tail
The bits round the missin part seem kind of brown could he have biten it off?
I have done a water test everything is normal

 

[Bettabelieveit]

could be a bite, what kind of plants are in the tank? are they plastic or silk? is there anything he can catch it on? otherwise it could just be fin rot.

 

[SRC]

Some bettas chase and bite their tails (like a dog), he probably did this, or it could have gotten caught in the intake tube (if you have filtration) when he swam close.

The brown could be the onset of fin rot though...you might wanna get some fin rot medications (of your choice. My preference is Salt and Stress Coat for minor cases and Melafix for advanced cases. Unless you have, or can get, some Indian Almond leaf ..which I would reccomend above all else if possible to acquire).

I would stay away from antibiotics unless it gets really bad (like half his tail is gone).