Betta Fish: May I present for your viewing pleasure: the 10,000th post questioning betta keeping’s greatest mystery: Fin rot, or nipping? You decide!

TLDR; Fin rot or nipping? Diamond eye and tumor? Kanaplex helped but more damage appeared within 12 hours of noticeable improvement.

I was finally able to snap a couple of good pics this morning. Stats:

Labeled “tangerine koi male” on his cup. 🙄 I’m assuming he’s actually a dragon scale, given the apparent scale growing over his right eye and possible tumor on his side. Thoughts? Diamond eye?

Brought home 7/4 of this year. Fish-in cycle. Planted tank, 10 gallons. Tankmates include 3 Amano shrimp, five Pygmy corydora catfish, and one mystery snail. Spiderwood driftwood, one rock structure, one floating betta log, sponge filter, and heater set to 78°F.

Parameters as of the most recent water change:
Ammonia .25 (my toddler “helped” me feed them)
Nitrites 0
Nitrates 20-30ppm (it was overdue)
KH is 4 drops and GH is 12 drops (API test kit). Whatever those measurements are

Zen’s fins have struggled for about 3 months now. I’ve treated twice with Kanaplex-saturated food, showing some improvement. However, the photos today show damage on his caudal fin that appeared within 12 hours. It was making noticeable progress and then suddenly turned ragged again?! I’m starting to wonder if he’s simply been nipping this entire time. There was one instance of a pinhole in the dorsal fin which did turn into a tear. It has not progressed.

I did notice when I first got him that when resting, his fins appeared to pull/drag him over so his spine was bent. I wonder if he’s just uncomfortable as they start to heal and he bites them off?

Please help me figure out treatment, if needed. I have aquarium slat on hand but have been putting that off as I don’t want to stress him unnecessarily.

THANK YOU!!! 🫶🏻