Not sure what’s wrong with my fish. Got this fish about 3 years ago. Always been fine, in a small tank. Moved him in to a 50 gallon tank, and randomly( few months in ) grows a big ball on his head looks weird looks like 50 small little bubbles. Not sure what’s wrong I feed him pebbles and used to feed him flakes I change/clean tank every few ( 2-3 ) months ( water always looks good ) can anyone help me out? Not sure if he’s in danger or pain. ( I tried to link a picture but didn’t let me)

  • 2
    If you struggle with photo uploads, make sure that you are not exceeding the size limit - aim for 2MB or less.
    – Stephie
    Feb 3, 2023 at 10:17
  • 2
    please add a bit more information about your tank,is it heated,do you have any filtration,what temperature do you keep in your tank.and please post the result of your last watertest,ammonia-nitrite-ph. Feb 3, 2023 at 12:05
  • 1
    Maybe you can also give some information what kind of fish it is... Feb 3, 2023 at 14:00
  • @Allerleirauh it’s a Gold fish.
    – Spliqbtw
    Feb 4, 2023 at 6:26
  • @trondhansen honestly. I’m not even sure. I had just used water from my house. Maybe that’s the issue he used to have clean water like those water things that fill up ur gallons, clean water. Then I randomly switched him to water from well water, but the well water is in good condition, maybe he wasn’t used to it. I was using a filter for about a month but it randomly stopped working so I never cared to fix it or get a new one. I’m not the best owner cause I’m not that informed on sertian things. But I always make sure to my fishes water is clean and feed him
    – Spliqbtw
    Feb 4, 2023 at 6:32

1 Answer 1


Your fish is inbred Ranchu Goldfish

From the description you're giving, I suspect your fish is a Ranchu goldfish, a breed of goldfish known for it's bumpy head produced by extensive selective breeding.

I believe the specific term is lymphosystist, a genetic disorder characterized by an extremely lumpy head, present in Ranchu breeds.

How do you get lymphosystist? your family tree must be a straight line, or, in other words, inbred as hell.

It may affect your fish's ability to breathe and may make him more susceptible to infections

  • 2
    welcome to pets.SE! Please give a source where your knowledge comes from. Feb 7, 2023 at 19:51
  • only vague memory, but from YouTuber AVNJ, an Ichthyologist from New jersey + random fish website rabbit holes, I'm sorry if this information is not valid enough Feb 7, 2023 at 19:54
  • Because we handle living beings here, sources are crutial to research further and evaluate the information. Maybe you can have a quick search and link a relevant video of the channel? Minimum the picture you have somewhere from in short history... Feb 8, 2023 at 6:22
  • @Allerleirauh alright, will get on that soon Feb 8, 2023 at 16:08

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.