I have never seen this before, and even better its not in my aquarium. My uncle has a small aquarium set up in a 10 gal
tank with a "skilter" for filtration. All seemed to be going well for the 2 years he has had it up and running. he has had a tomato clown fish for the same 2 year period. Everything was going fine until tuesday when i noticed the fins were starting to fry.... but it just got worse from there. the fraying continued til saturday night when the fins and belly started to "blister"(worse on fins). i have no idea what it is, i will try to get a picture if i can, it may help to illustrate the problem. thank you in advance for your time and help.