Looking for advice…

Calypso · 2026-11-06T08:16:49-0600

Hi. New to this forum but looking for advice. Avid fish keeper for over 30 years. Have had saltwater tanks for most of my fish keeping years. Recently embarked on keeping a small 13 gallon fresh water tank with live plants, a beta and two Cory’s with some shrimp. Looking on general fresh water fish health. Recently my betta developed this white growth on her dorsal fin. It is at the bottom of the fin both sides. I moved her to a hospital tank and did a treatment of API gin and body cure but that did not seem to do much of anything. I have now just done a course of kanaplex and it might have diminished a little but is still there. I have not been able to identify what it is. Any help would be appreciated. I have included pictures. She is swimming and eating. I have included two photos, (hard to get close ups as she is swimming around). Main tank has been up and running with live plants for over a year. All water perimeters are fine. Right now the betta is in a small three gallon hospital tank while I was dosing with kansplex.
Thank you .

Jennet · 2026-11-06T09:50:41-0600

Hello and welcome to the forum. I have no experience with Betta, but I am sure someone with experience will be along to help you soon.

TNG · 2026-11-06T21:16:12-0600

Welcome to TFF.
You may receive more responses if the subject is changed from New to Forum to Looking For Advice.
What I can see from the photos is a fat betta, assuming it's not swollen. The white stuff at the base of the dorsal fin is concerning but it's impossible to tell what it is. A photo in-focus from the side of the fish would help, although it may be impossible to achieve if the photo is taken through an acrylic container.
You also mentioned all water parameters are fine, so that leaves us wondering why then is the betta not fine? What are your GH and pH? The tank has been running for over a year so it's well cycled, but how long have you had the betta, the cories and shrimps? About a year or are they recent additions? A photo of your 13G tank would also be helpful.