What is this?

Question
We have had our beta fish for 3 months now, and he's been fine. But just today, I discovered between his fins is a brown, intestial-looking thing hanging down. It's medium size, but he is swimming, eating and doing fine. Is it a tumor or is it his intestial tract? I'm quite worried.

Answer
Hi Bobbie;

Maybe he injured himself somehow, or it could even be as simple as a case of constipation. If his intestines have prolapsed (fallen out)or he has a tumor, there isn't much you can do anyway. Just keep his water very clean and feed peas a couple of times a week to prevent constipation which can even cause prolapse or make it much worse. Break off tiny chunks of a peeled green pea and feed one to him instead of his regular food that day.

At Your Service;
Chris Robbins