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My betta fish is sick with fin rot and lethargic. How can I save him?

Updated on September 23rd, 2025

Pet's info: Fish | Betta | Male | unneutered

Hi; I have a betta I purchased about 3-4 months ago. He started to get fin rot, so i purchased Bettafix and did a 100% water change. However since yesterday (first day with bettafix) he is lethargic; all day today he was at the top (by the heater which keeps his tank at 78 F) but now hes at the bottom. Looking almost lifeless. Is there any way I can save him?

3 Answers

Most Helpful Answer

Answered By Todd Cecil

Veterinarian

Published on February 26th, 2019

Thanks for reaching out about Flippy. A veterinary visit is highly recommended. Testing water quality for ph, ammonia, nitrites and nitrates, correcting any concerns. Water must be dechlorinated for several hours at least, prior to adding to the tank.
Laying on the bottom could be a sign of a swim bladder infection and loss of buoyancy. Systemic antibiotics, not water additives, are recommended.
Bettafix as a water additive does little for systemic infections.
Good luck.

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Dr. Dayna, DVM, CVA
Veterinarian, Certified Veterinary Acupuncturist
Published on October 7th, 2017
The pet stores all have water additives you can use to help. I’ve used the melaleuca products in the past that have worked well. Continue to do frequent partial water changes and keep the water chemistry well balanced. Good luck!
1Pet Parents found this answer helpful
Answered By Rebeccah Wood
Licensed Veterinary Technician, Registered Laboratory Animal Technologist
Published on August 13th, 2017
Hello there! I'm sorry to hear that Moses has fin rot. Fin rot can be caused by either a bacteria, a fungus, or sometimes both. You're doing well by changing the water (though 20% once weekly should be sufficient - you don't want to remove too much of the tank's natural bacteria as they are what help keep the ammonia level low and maintain a natural homeostasis). Some fish experts suggest adding freshwater aquarium salt to the tank to help treat fungus at 1 teaspoon per gallon of water. Be sure to use salt made for freshwater aquariums - not table salt or marine salt. If this does not help, it may be bacterial, at which time you should contact an aquatic veterinarian or specialist for treatment options. Good luck, and I hope Moses recovers!
3Pet Parents found this answer helpful

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