How to Cure Fin or Tail Rot on Your Pet Fish with Peroxide

Aquarium owners know that some illnesses in fish aquariums just won’t go away, regardless of what they try. However, there seems to be more than one way to solve some fish illnesses and sometimes those involve using regular household products. Fin and tail rot can be cured, and quite easily by using regular peroxide.

First, you’ll need to prepare for this process, which some fish owners call ‘surgery’ but is far from that. Set aside a cup of treated tap water. This cup of water will be used to rinse your fish later. Take your fish and place him in a smaller container, one of which that can be easily transported to and from the closest sink. Have another container on hand with treated, room temperature water so you can place your fish into the new, clean water. You will also need a fish net, some paper towels (one paper plate and a paper towel can be used, depending on your preference), a bottle of peroxide, and some q-tips.

Lay out a clean paper towel (or paper plate, whichever you are using) and fold another paper towel over and over to make it small enough to cover the head of your fish. Dip this paper towel in clean, treated water and set it aside. Take your fish from his cup and place him on the paper plate. Quickly cover his head with the wet paper towel and hold the two ends. This will help calm him, and keep him from flopping if he gets frustrated.

Next, you’ll dip one end of a q-tip in the peroxide and begin to paint your fish. Very gently slide the q-tip over his fins, making sure to get any blackened edges, or area’s of the fin that the rot seems to occur on most. The fin may ‘fizz’ or bubble a bit, but this is common, especially if their fins are being attacked by a lot of bacteria or fungus. You may also notice a bit of blood or a blackish looking substance on the end of the q-tip. This is completely normal.

You’ll want to leave the peroxide sit on their fins for a few seconds. Make sure that you only paint the fins and nothing else. Do not get the peroxide near his gills because this can cause complications, even death. After the peroxide has set for a few moments, remove the paper towel and dump the fish into the net. Take the treated water that was set aside earlier and dump it over the fish. Continue until the entire cup is empty. Shake him off and put him into the other container you had set aside earlier.

Your fish may act very angry after this process. He may quickly swim around, or shake out his fins as if he was trying to remove something unseen. For the next 24 hours, his fins may seem dull and colorless; they may even look ‘melted’. Don’t worry, this is normal. Some fish may act a bit shocked, and sit at the bottom of the tank without swimming much. You can make them comfortable by covering their tank in a towel and checking on them every so often. The towel minimizes outside stressors. Products such as Melafix or items that help replace their slime coating are excellent items to add to a tank after a painting. This helps replace the slime coating which ensures that electrolytes are not lost, which can be harmful. Aquarium salt can also be used which also helps replace electrolytes and it helps reduce fish stress. Add no more than the recommended dosage.

And remember, this should only be performed if you are comfortable with the process and after all other treatment methods have failed. Perform this treatment at your own risk.