I'm interested in how things are going there.
I have a fish doing the same thing. The ends of the fins look like they are thinning and tearing. Overall color on the rest of the fish looks fine. Appetite is great and he is very active.
Here are before and after pics..
Here is a video before..
10 gallon divided running for less than 1 month so far.
Under gravel filter with 10g AquaClear power filter connected to it running 24/7 with redirected water flow, other side has a stone to provide better water flow.
Temp stays steady at 78, currently just above 80.
Tank was not cycled before starting, water was just changed 40% with gravel cleaning. Used mix of purified and recovered water.
Water is very hard, was lowered a bit with water change, reused some of the old water to control Ph drop.
Nitrates, Nitrites and chlorine are nil.
Alkalinity has been 300+ but has dropped under 300 now.
Ph looks to be close to 7.8 now but was highest reading before water swap.
I use a dechlorinator on tap water and have used a TopFin Bacteria Supplement in the beginning and after the water change, 5ml as directed.