I can’t tell if it’s a fungal disease, but he lost all of his color. My sister never cleaned his tank so I think that might be the reason behind it, but I don’t know what disease he has so I have no idea of treating it. I put him in a separate tank with clean water, will he just get better on his own? He won’t eat.

enter image description here

enter image description here

  • 1
    welcome to pets,please give more details how large are the tank any filtration and heating is the tank properly cycled what do the watertest show amonia-nitrite-ph.please take a look here on how and why cycling a tank is needed fishlore.com/NitrogenCycle.htm Commented Jan 30, 2019 at 5:29
  • Our tank is basically this: petswarehouse.com/… and we use natural drinking water (not tap) and we use API stress coat on the water.
    – S. Whiye
    Commented Jan 30, 2019 at 15:56
  • 1
    i miss the result of the water test and the answer about if you cycled the tank BEFORE you got the fish,in fish keeping there are no shortcuts and stresscoat can be helpful for your fish after the tank have been cycled. Commented Jan 30, 2019 at 18:47
  • 2
    Possible duplicate of How can I help my betta who is laying at the bottom of his tank? Commented Jan 30, 2019 at 18:49

1 Answer 1


It's always hard to identify when a fish is doing poorly. But what I always recommend is making sure they have the right environment. That's always key to having a healthy fish. Once they're in the right environment, if they still don't get better, then you can look into further treatments.

Your fish needs at least a 5 gallon (19 L) tank. Think of it this way: You could live in a box if you were given food and water, but would you be happy? No. Your fish needs space.

Then, make sure you have a water heater to keep his tank a constant warm temperature. Make sure when you add new water, it is as close to the same temperature as possible. You mentioned you use drinking water - is it distilled? Because sometimes distilled water is missing some important nutrients needed by fish. If you use tap water with a water conditioner, he would be just fine.

Filtration! Trond Hansen posted a link to the Nitrogen cycle above. Fish waste and discard food cause high ammonia levels, which are extremely harmful to fish. Filtration will help with this (though you still need to do regular water changes), and it also encourages good bacteria to grow.

Finally, make sure you're testing the water for all those chemicals. This can help you identify if it is incorrect levels causing your fish's illness. Check pH, Nitrates, Nitrites, Ammonia, and water hardness. If your sister never cleaned his tank, it's likely the ammonia levels were too high.

Once you are able to transfer him (slowly! acclimate him first) to his new environment, keep a close eye on him to see if he improves.

Best of luck to you and your fish!

  • 3
    Hey, fantastic answer here :) Thanks for posting it!
    – Henders
    Commented Jan 30, 2019 at 21:37
  • "[...] sometimes distilled water is missing some important nutrients needed by fish [...]" technically the mineral nutrients are always missing from distilled water because the process of distillation removes them all (some negligible amounts of not-yet-distilled liquid water could get aerosolized as a fine mist and - together with the original mineral content - pass all along to the condenser, but I'd expect this to be next to nothing in industrial water distillation units) - so it's safe to assume that distilled water is completely devoid of them. I am sorry if you are already aware ...
    – lila
    Commented Mar 13, 2021 at 0:03
  • ... of this and know that minerals are always absent, maybe you meant that it's the fish who aren't always deficient in these minerals? It is not clear for me, so I prefer to leave a comment, thanks.
    – lila
    Commented Mar 13, 2021 at 0:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.