I may have rescued a betta that has Mycobacterium. He is currently in a clear plastic tote in 1 gallon water. I feel so bad for him, that I want to move him to a 5 gallon tank. While I researched about how to sanitize the items if or when he dies, I found various articles about povidone-iodine's effect on Microbacterium spp., in vitro to be 99% effective. So, my question is, can I use this to disinfectant the tank and stuffs in it?

Here is one of the articles.

  • For clarification: What exactly do you want to disinfect? Water? The quarantine tank (assumption: no interior)? or the 5 gallon tank with interior? Jan 4, 2021 at 19:31

1 Answer 1


Using povidone iodine in your tank is not a good idea it is harmful for most water living animals and it will stain most plastics.

If you want to do a total disinfection of your tank it is better to use hydrogen peroxide, as this breaks down to clean water.

Remember, after you have disinfected your tank you will need to cycle it for a month or more; cycling is done to build up bacteria that convert waste into plant food.

More information and details about cycling a tank could be found in this article.

Every time you disinfect or treat your tank with antibiotics you will have to cycle the tank again, the best way to avoid this is to medicate your fish in a separate tank.

The main reason for fish getting ill is a result of poor water quality, this is caused by overfeeding or not cycling the tank properly.

Before you go out to buy fish, take some time to read about the needs of the fish you want.

  • hello, thank you for your answer. Yes, I'm aware of nitrogen cycle and Yes, I have a separate hospital tank. and I disinfect it after quarantining new bettas I rescue Bettas from local owners who couldn't take care of it and also sick bettas from local chain pet stores like petco and petsmart. My question was how to disinfect after he dies and he does not show any symptoms other than a rash looking thing on his gill plates. This particular fish is currently in my hospital tank and I need it to quarantine my new rescues. WHich is why I plan on moving him to a 5 gallon. Jan 3, 2021 at 7:53
  • Based on my research, Mycobacterium has extra layer of protection and hydrogen peroxide/ chlorine is not effective in disinfecting the tank or tools used in the hospital tank. I also try as much as possible to stop waste going to dumpsters and would like to disinfect the tank instead of just throwing it in trash and my question is if Povidine Iodine is effective in killing Mycobacterium. Jan 3, 2021 at 7:55
  • povidine iodine are used on the skin before surgery and to treat infected vounds,it is not used to disinfect water.my answer to you is i do not recomend using iodine in your tank,what you do with my advice is up to you. Jan 3, 2021 at 8:23

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