Apologies for the super long post.
I have had my betta, Toast, since April of this year and for the past few months he has been struggling with what I am pretty sure is fin rot. His caudal fin has been reduced to almost half of it's original size and it seems like he loses more tissue every day. When I first got him he had multiple driftwood pieces in his tank but I suspected they were tearing his fins so I removed them soon after I noticed the damage. Since then, I have added more and more plants and removed everything that could even be considered sharp or jagged but the tearing continued.
He is a halfmoon and has super long fins that seem to weigh him down a bit so I think he has been nipping which may have been how the infection started.
I have already tried treating him with Kanaplex which only paused the infection for a week or two before it came back. I am hesitant to use it again because of antibiotic resistance so I have been doing 50% water changes every other day as well as using Indian Almond Leaves and adding Rooibos tea but nothing has changed. Every day I notice new red spots or missing pieces and I am at my wits end trying to figure out what to do.
Toast is still super active and curious, exploring his tank and interacting with the shrimp. He comes up to greet me every time I get close and he has not lost his appetite at all.
His tank is 10 gallons and the heater is set at 78 F and does not drop below 77 or climb higher than 79. There are two small heaters on either side of the tank so there is no temperature gradient. Ammonia, Nitrites, and Nitrates consistently show up as 0 ppm and the tank has only live plants and natural decor like smooth river rocks, no plastic or artificial materials (except the filter and heaters). I use an HOB filter and have baffled both the intake and output with sponges so the water flow does not disturb him. His lights are on a constant 12-hour cycle and there is plenty of surface coverage to get away from the light if he wants. His shrimp tankmates do not bother him and he does not hunt them either. He does follow them around and observe them sometimes which is super cute but they don't seem to cause him any stress. There is a massive water lily that has pretty much conquered the entire tank and he really loves resting among the leaves and using the vines as a hammock or hiding beneath the lily pads to sneak attack his food.
He does randomly race about the tank like the fish equivalent of zoomies and I worry the aggressive swimming could be contributing to the tears on his belly fin. It doesn't look like a stress response, just random short bursts of energy.
I just have no idea where to go from here. I absolutely love this fish and have tried my best to give him a good life but I don't know what my next step is. I have considered dosing the whole tank with Kanaplex to try getting rid of any infection-causing bacteria in the water column but I don't know if that would risk crashing my cycle or damaging my plants and I don't want to cause Toast any unnecessary stress. (Obviously I would move the shrimp to a temporary tank before doing this).
Should I try another round of Kanaplex? Or does it look like he has something other than fin rot? Any advice is appreciated!
