What is this???

Smalltank3

Large Fish
Dec 23, 2005
961
4
0
Wisconsin
#1
Hey everyone. I noticed a couple days ago that my female ram's tail was kinda of split in towards the top. I first thought it was fin rot but none of the pictures I saw looked nothing like this. It just looks like a rectangle between her tail with a white thing at the end. I have nothing that would possibly nip at her tail, 2 otos and 2 ADF's. The pic is sort of blurry but the tail is clear to see. Here it is:

Does anyone know what this could be?