Fin help

[we3shipps]

My betta, Ariel, has this ??? i dont even know.. but this tiny part of the back of his tail is gone.. i 1st noticed it when he was upset about us getting him a snail. i quickly dismissed it as a temper tantrum. The snail has been gone for a while and the little part may possibly getting worse (slowly)
since the picture isnt the greatest quality, i'll describe it then post a pic
Ariel is a vibrant red with very flowy fins. The part in question is void and the edges of the void is a darker red possibly even black. The edges of the rest of his fins are translucent. I sure hope it was simply a temper tantrum and not some sort of disease.

[we3shipps]

(i dont know how to put a bigger copy of my profile pic on here) but my profile pic is of him in a newly cleaned tank just after i took his snail "friend" out.

[Sapphoira]

Do you have any decorations with sharp edges? Each decoration should pass a panty hose test for those fish with long fancy flowy fins! Could also be fin biting, fin rot, etc. That picture is reallllly hard to tell anything from though!

[cjconcepcion]

im 99% sure this was the result of tail biting, probably because of the snail. he may do it again or he may not, i had one fish for over a year and then last month he started eating his tail for no reason. just keep his water super clean and he will heal up in no time!