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Anna, Pet Expert/Biologist
Category: Pet
Satisfied Customers: 11512
Experience:  40 yrs.: herps, pocket pets, rabbits, poultry, dogs, horses. Biology degree. Vet assistant.
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Betta Fish Question...Please respond only if you are a hands-on

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Betta Fish Question...Please respond only if you are a hands-on betta fish person. Thank you.

I would like to find out how to treat severe fin rot in a betta fish. The fish's dorsal fin is almost gone and in the spot where the fin grew out of the body is now a rather "big" lump of tissue (I guess) under the scales. So far, I have tried melafix with almond leaf, extra aquarium salt, and more water cleaning (change half of the water in the tank every 2 days). At this point, I am about to try Tetracycline. Is there anything that works that I could try?

Thank you.

Hello Saso,

My name is XXXXX XXXXX I'm a biologist who has owned bettas for many years. I'm sorry to hear of your fish's problem. Aqaurium salt works well for mild fin rot. Melafix will do nothing at all for it. At this point, your betta has fin rot that has spread to his body, and it will take real antibiotics to clear it up. This infection is usually caused by gram negative bacteria. Maracyn 2 is most effective against this type. Other antibiotics, including tetracycline can be also used, but I've found the Maracyn 2 to be most effective.

There are some other things to consider. The tank should be kept at 76*F to 78*F becasue those temperatures inhibit the growth of the bacteria. Water quality must be perfect. I would do a 100% water change, using water that has had the chlorine removed and is the same temperature as what is in the tank. Remove carbon from the filter. Then treat with Maracyn 2 according to the package directions. If water conditions are not kept perfect, no medicine will work. It's best to test for ammonia and nitrites every day. You want them at zero.

If you have more questions, let me know by clciking on REPLY. I hope your betta will reach a full recovery.


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Hi again,

I have one little addition. If you have a filter in the tank, you may want to keep the filter media to replace it after treatment. The antibiotic treatment does kill the good bacteria, but if you keep the filter media wet, some will survive in it. You can then put it back in after treatment, giving you a head start on re-establishing the beneficial bacteria.