Can someone please help. We have just brought a tank off a lady and she gave us the fish aswell. There’s definitely something wrong with this fish and I just want to know how to help them and give it a good life. Any advise would be appreciated Thank you
First off your fish is not a Betta but a fancy Guppy.
I'm not really sure what is going on with the fins though as I've never seen anything like it before. It's possible it is lymphoma which as far as I know has no treatment besides maintaining low organic load in the aquarium by frequent substrate vacuuming to remove uneaten food and debris, regular filter media rinsing and regular water changes.
How large is the tank and are there any other tank mates with the guppy?