Avi
Aquarium Advice Activist
I have a variety of Corys in one of my long-established freshwater community tanks (60-gallons - tetras, small barbs, dwarf gouramis, etc. … no aggressive fish) and...I guess because of the addition of a new fish into the tank recently that exhibited no signs of any disease...a few of them have contracted a disease that resulted in their deaths. Here's a photo that shows the initial symptoms. That lightened area is clearly defines (not the result of any photo-software highlighting though that's what is almost seems to be.) The photo shows how it is very pronounced around the base of the dorsal fin but also shows that it appears at the adipose fin on to the top of the tail fin, as well. Can anyone advise as to what this disease is? Thanks.
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