swim bladder disease

Swim bladder disease

Swim bladder disease

When I write articles for the blog, I generally get my ideas from one of four sources of inspiration:

  1. I try to think of a mistake I made in the past and write a post that would have helped me avoid making that mistake.
  2. I pass on the information from something I’ve learned recently
  3. I write about something happening with my own aquarium

Well, the post this week is about swim bladder disease, and unfortunately, the inspiration is from my own tank, as I sought the answer to the question:

Why is my clownfish swimming on its side? Or Swimming with its head down, bobbing, and then returning to swimming sideways? It’s like it became a cork all of a sudden.

Swim bladder

Swim bladder

What is a swim bladder?

Bony fish have an organ in their body that helps them stay buoyant and upright in the water. The organ is filled with gas and is called a swim bladder, glass bladder, or air bladder. A healthy fish without any disease affecting the swim bladder can inflate and deflate the organ to keep an appropriate level of buoyancy.

Fish Swim BladderCartilaginous fish, like sharks and rays, do not have swim bladders. But unfortunately, many fish who become ill lose the ability to control their buoyancy. That seems to be the problem with my clownfish right now.

What is swim bladder disease?

Swim bladder disease is a term used to describe a sick or injured fish unable to hold itself upright or maintain its position in the water column. My clownfish have adopted a toadstool leather coral as their anemone surrogate, and that is where they have hung out for the past couple of years. But a few days ago, my female clownfish started showing signs of swim bladder disease.

What are the signs of swim bladder disease?

The most prominent sign of swim bladder disease is a fish that is unable to swim normally. The fish looks like it is having problems staying balanced or upright in the water. Sometimes, fish with swim bladder disease seem to bob back and forth in the water, darting down and then bobbing back up. Other times they may just look like they’re laboring or swimming really hard just to stay in place. For my clownfish, the signs were that she was no longer nesting in the leather coral and was lying on her side at the surface of the water, swimming sideways. Ugh.

It seems like she is rasping at the surface (trying to swallow air?). She is still eating. She rights herself and swims in the current of the return pump, and then drifts back to lay on her side at the surface in the middle of the tank.

swim bladder disease

Image by L Church

What causes swim bladder disease?

Unfortunately, like a few of the maladies that affect saltwater aquarium fish, swim bladder disease does not appear to have one specific cause. There are a few theories:

  • Trauma/Injury
  • Bacterial infection
  • Parasitic infection
  • Stress/rapidly changing water parameters
  • Poor water quality

My water quality appears fine, but I’m going to do some water changes just to be extra cautious. I don’t believe there were any rapidly changing water parameters–and there were no major changes to the tank recently, so in my case, I’m narrowing the possibilities down to Trauma or infection. It’s hard for me to assess whether the trauma was the primary cause. My clownfish tend to squabble a bit, but I didn’t observe any out-of-the-ordinary fighting before noticing my sick fish, but there is certainly a lot of fighting now. The male routinely swims up, shudders, and takes a nip at a fin or tail.


Since swim bladder disease isn’t caused by just one thing, the first step in treating swim bladder disease is diagnosing what you think the primary cause is.

To treat a sick fish, be sure to remove it from the display tank and treat it in the quarantine/hospital tank. That will allow the fish to recover without being harassed by the other fish and enable you to medicate in a smaller, controlled environment.

If the fish is suffering from trauma, a little rest in relaxation in a hospital tank may be all that is needed.

  • Treat a bacterial infection with an antibiotic.
  • Treat parasites with copper or medication specifically labeled to kill parasites.
  • For rapidly changing water conditions, identify the problem causing the changes, and eliminate it. Heat water before doing water changes, replace faulty heaters or equipment, fix the problem, and do a water change.
  • The cure for poor water quality is water changes. Bacterial and Parasitic infections can be treated with aquarium pharmaceuticals (antibiotics for bacterial infections and an anti-parasitic agent for a parasitic infection).

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Here’s to hoping your fish (and my fish) get better soon. Do you have any solutions? If you do, please let me know in a comment below.


    1. Author

      Hi Oliver, thanks for the comment/question. The only thing definitive I’ve read in Dr. Noga’s textbook, Fish Disease: Diagnosis and Treatment that there is a nematode Anguillicola that infects swim bladders, but I believe that to be a freshwater problem. I was using the term to more generally describe when the fish no longer has control of the swim bladder to maintain their position in the water column. Have you observed this or do you have experience here?

  1. How is your fish doing? I have a clown that has it and it seems to be stress related (i just got him and he had it when i got them, i was hoping i could nurse them back or just give the clown a nice home in my tank) I have no other fish and I’m keeping my water consistent. How long did it take your clown to get better?

  2. its so cool that u have such a bond to ur fish and are able to hold them like like I did in video thats so awesome you could totally tell that the fish was comfortable especially when he swam back up in ur hand when u let him go the first time. that’s really special. I have a clown fish and its not doing well I believe its swim bladder its been like this for quite some time. I think it had something to do with me changing the salt brand not by choice just thats all I could get. im still very new at all this so I didn’t know changing ur salt brand could do such things to ur tank. do u think that having a lower salt level rather then on the higher side is better for the fish??

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