Test your water and make sure that your ammonia, nitrates, and nitrites are at proper levels. If they are not, change 20% of your water no more often than every 2 days. Make sure to test your water before you change it again, in case you don't need to.
Once you are sure your water is at proper quality, treat with antibiotics you can buy at the pet store. Make sure to keep your water quality and filtration is in tip top shape, because fin rot usually is caused by substandard water.
Chat with our AI personalities
You can't. You will need a heater to increase the temperature of the water to approx 78F, some medicine, aquarium salt, and melafix