Help for Cory catfish

[MNora]

Hello, new person here. I have a corydory catfish that has developed this black bulge/spot on its belly. I don’t know if it’s a bad thing. Can someone help me? It seems to be swimming well and no behavior changes, but I am just concerned and would like to know what to do, if anything. Thank you

[Colu]

It could be a number of things such as an injury causing hemorrhaging or a  growth or a bacterial infection what I would do is quarantine and add some Indian almond leaves as they have antibacterial and antifungal properties depending on the quality of the leaves you might have to add one leaf per gallon to get a beneficial effect and I would add some aquarium salt 1 table spoon for 3 gallons I wouldn't go above that level with salt as Cory's are more sensitive to salt for a week give an update if it start to get worse before then@MNora