Thank you I quarantined him/ completely cleaned out his tank( I have a 10 gallon tank) I removed all of the accessories& plant -refilled his tank chucked all the accessories /hooked up his filter and the water heater. had three sticks to test the water( I used them all ) in order to lower the nitrates I put his plant back in and he's been floating up top for the past half-hourHeron said:The best treatment for finrot is very clean water. Salt also helps but only short term. With other fish I would recommend mellafix but I was told this is not good for bettas. When Arnold my betta had fin rot I did daily water changes of about 20 percent. For a few days I added 1.4 grams per litre of aquarium salt to the new water then I continued water changes without salt for another few days to reduce the salinity back to nothing. This stopped the rot and the fins began to recover.
Make sure the salt is fully dissolved in the water before adding to the tank
There are meds. out there for fin rot which may help but good water quality is by far the most important thing.