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My balloon molly has a damaged fin. What caused it? How to help?

Updated on September 23rd, 2025

This is a balloon molly and i noticed that the fin has been damaged. I dont know why it has happened, can you tell me why? I keep 3 balloons in my 20L tank and he is the most aggressive so i dont think the others did it to him. I feed them tropical fish flakes and frozen brine shrimp in turns and do water changes once a week. Can this condition be fixed? if so, how can i help him?

1 Answer

Most Helpful Answer

Miranda Sadar, DVM, DACZM

Answered By Miranda Sadar, DVM, DACZM

Veterinarian

Published on July 16th, 2019

Thank you for reaching out about your molly. Unfortunately, the fins are not very good at regenerating themselves completely, so your fish may always have a bit of a scar/missing parts of the fin. I also see that there is a potential scar/white area on the side of the body? These two together may be from this fish getting caught on something within the tank, or from trying to wedge himself into small areas where he can get caught. It would be less likely to be an infectious agent, such as a bacteria or parasite, or an environmental/water issue as the other fish appear to look okay in the photos from what I can tell. I would suggest trying to look very closely at the tank furniture and the fish's behavior to try to identify where it may be getting injured. Alternatively, you can partition out a portion of the tank for this fish to reside in for a period of time to allow the injuries to heal. This would also allow you to be able to rule out whether it is trauma from one of the other fish as well.
I hope this gives you a place to start, and thanks for using Petco Pet Education Center, formerly Petcoach.
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