I noticed last week that Ernesto's fins looked a little ragedy...so I did a scrubdown/100% water change on his 2 gallon tank last Sunday (I usually do a 50% 2X weekly).
I noticed this morning that his back fin looks like a bite had been taken out of it...(he is a lone fish dictator in his tank). I think that it is finrot, and do not know how to take care of it other than water changes! Help!
BTW, He is active and eating just fine, so it perplexes me.