What do you do if your fish’s fins and tail are looking ragged or discolored? It may be a bacterial disease called fin rot. This illness is simple enough to treat but can lead to other serious complications if left unchecked, so follow our five easy steps for curing fin rot.
Fin rot is commonly found in aquarium fish such as betta fish and goldfish. The symptoms can vary based on how long the fish has been affected:
Stage 1:The fins and/or tail start show some discoloration, especially on the edges. Depending on the original color of the fish, the discoloration may appear as white, red, or even black.
Stage 2:The fin edges look frayed and uneven as infected pieces start to die and fall off.
Stage 3:The entire fin and/or tail has rotted away, and the infection begins to attack the body, potentially leading to loss of life.
You may also notice your fish seems listless or doesn’t feel like eating anymore, since its body is working hard to fight the infection.
If your fish naturally has uneven fin edges, you may have difficulty spotting fin rot.
Check your fish’s environmentWhenever your fish gets sick, the first thing you need to do is play detective and find out why the fish got sick. Fin rot may come back again unless you remove the cause of the problem. Check the water parameters with an aquarium water test kit to see if anything is out of whack. Make sure there are no environmental factors causing stress to your fish, like an overly strong filter, sharp decor, or wrong temperature.
Take corrective measuresAfter you discover what’s wrong, remove the source of stress immediately so your fish can start recovering.
Clean the fish tankMedications often require you to hold back from doing water changes during treatment, so clean the aquarium and remove as much fish waste as possible. (Read our tutorial on how to properly clean your aquarium.)
Treat with medicationsWe recommend using a broad-spectrum antibiotic known as erythromycin that is effective against fin rot. If your fish has also developed a secondary fungal infection, methylene blue is an appropriate antifungal treatment.
Make your fish very comfortableKeep your fish’s environment very clean and comfortable to ensure a quick recovery process. Medications can sometimes make the water harder to breathe in, so add an air stone or sponge filter to keep the water well-oxygenated.
If you cannot buy erythromycin in your country, try treating the fin rot with aquarium salt. Just be aware that this method generally takes longer to cure the infection. For more details, read our full article on how to treat fish diseases with salt.
Fin rot can be caused by dirty water, nipping from other fish, or other stress factors.
The medication may take several days to beat the infection, but some clear signs of recovery include:
In the meanwhile, you can do several things to prevent fin rot from coming back. Dirty water is a common cause for bacterial infection, so schedule a regular time for cleaning the aquarium and put a weekly reminder in your phone so you won’t forget. Other ways you can keep the water cleaner include not putting too many fish in one aquarium, not overfeeding them, and adding live plants to help absorb some of the fish waste.
As mentioned before, continue to reduce any stress factors in the aquarium by maintaining the proper temperature with a heater, slowing the water current if needed, and removing any aggressive tankmates. Finally, keep a close eye on your fish. It’s easy to miss symptoms if no one’s paying attention to the aquarium, so we recommend examining your fish once a day when you feed them.
Take heart! With proper treatment and prevention, fin rot is an easy sickness to beat, and most healthy fish have no problems making a full recovery. For information on how to treat other fish diseases, see our other articles here:
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