Swim Bladder Inflammation in Fish

Swim bladder problems are somewhat uncommon in saltwater aquarium fish.  They’re commonly found in deepwater fish that are not properly decompressed, sometimes in fish with digestive problems (commonly due to a poor diet), and occasionally due to the presence of viruses, bacteria, and/or parasites.

Treatment Background

If the fish was not recently acquired (within a few weeks) and is not a typical deepwater fish, then I would suspect the diet or infection.  If the fish is not in obvious distress, then changing the diet is the most easy solution.  If the fish is in distress, then it may require treatment alone in a hospital tank.

Problem Identification

Typically the fish will initially present with a head-down, tail-up swim position.  It may look slightly bloated or appear to have a very full stomach.  As the problem progresses, the stomach area will continue to enlarge and the fish may begin to float on its back or side.  Identifying the problem early will help prevent other internal organ damage.  Keep in mind that not all swim problems in fish are from swim bladder inflammation.  Erratic swim behavior may be caused by an infection affecting the fish’s ear ossicles, liver, or intestines.  If the liver is enlarged or the intestines are blocked, the swim bladder may be affected as well.

Tilefish Floating on its Side

Tilefish Floating on its Side

Some fish that have access to the surface have “open” swim bladders, which means they can regulate their buoyancy by gulping air.  Deepwater fish typically have “closed” swim bladders where a gas exchange occurs between the blood and the swim bladder.  If deepwater fish are surfaced too quickly during collection, the trapped gases expand and do not have a quick exit route.  This may lead to internal organ damage.

Treatment Options

Diet Change

As mentioned above, changing the fish’s diet (if not in obvious distress) is probably the easiest, cheapest, and lowest stress (to you and your fish!)  If your fish isn’t a deepwater fish (you’ll probably know based on the amount you paid for it – deepwater fish are notoriously expensive), then I would recommend starting here since the fish probably has an open system.  A swim bladder problem could be caused by the diet affecting the intestines or causing the fish to gulp excessive air.

If you are currently feeding floating foods, try switching to sinking foods.  This will decrease the amount of air that the fish is gulping.  Next, take a few peas (yes, the ones in your kitchen…just thaw if frozen), and pop them.  Remove the outer shells, and feed the inside mush to the fish.  You may need to mix it in with the fish’s regular food to ensure it is eaten.  Repeat this daily for about two weeks or until the problem subsides.  If the problem does not go away or worsens, more drastic measures may be required.


Various bacterial diseases may cause swim bladder issues by affecting the swim bladder itself, the intestines, liver, ears, you name it.  If the fish is a shallow-water swimmer and a diet change has not helped, then antibiotics may be required.  Since I’m not a marine fish pathologist (and if you’re reading this, you probably aren’t either), I prefer to use a broad-spectrum antibiotic like Furan-2 and follow the manufacturer’s recommendations.


In viral cases, there isn’t much that can be done other than to wait out the infection.  Again, if you aren’t a fish pathologist, you may want to go ahead and try a diet change with antibiotics to help rule out other causes.

Treat for Parasites

Another potential cause is internal parasites.  I prefer Prazi-Pro to treat (follow manufacturer’s recommendations) since it targets a wide variety of parasites.

Vent the Swim Bladder

And, here’s the ultimate purpose of this blog article.  I recently learned how to vent the inflamed swim bladder of a fish that was not properly decompressed.  Unfortunately, it did not make it (likely due to internal organ failure), but the procedure was successful (the fish could swim properly afterward).  I do not recommend this procedure if you have not tried all of the above methods, if the fish is not a deepwater fish, or if you are at all squeamish.

I found a flashing tilefish (Hoplolatilus chlupatyi) at a reputable LFS for a good price.  It looked healthy, but I knew decompression signs could show up later since it was a deepwater fish.  I took the risk.  During the first several days of quarantine, the fish was happy, eating well (sinking foods), and showed no signs of decompression sickness.  Later, it started to swim head-down and appeared to exert a great deal of energy to maintain this position.  I tried the mashed peas with no luck (it had already gone through an antibiotic and Prazi-Pro treatment as well).  Eventually, I came to the realization I would need to vent the swim bladder.

Tilefish Exhibiting Swim Bladder Problems

Tilefish Exhibiting Swim Bladder Problems

I researched across several reefkeeping sites and forums with little luck on how to perform the procedure.  Eventually, I found several fish and game websites that offered vague information on how to vent saltwater fish from the deep during catch-and-release fishing.  I did not save those references, so I apologize for the lack of references included here…and thank those unnamed sites immensely for their help.  However, there is a link to additional information from Mote Marine Laboratory below.

Equipment Needed:

  • 1 syringe (I used one obtained from a local pharmacy for insulin injections)
  • Rubbing alcohol (also from the pharmacy…nothing crazy)
  • Iodine
  • Strong light that can fit under a translucent/transparent container
  • Translucent/transparent container with a flat bottom
  • Gloves (puncture proof/resistant)
  • Safety goggles/glasses
  • Q-tips (or similar small applicator)
  • Broad-spectrum antibiotic (optional for recovery)


  1. Cover the light source with the container.  This will backlight the fish to help you see its swim bladder.

    Makeshift "Operating Table"

    Makeshift “Operating Table”

  2. Don all safety gear (gloves and glasses/goggles).
  3. Prepare your work area.  Have the syringe and chemicals ready.
  4. Carefully place the fish on the flat surface of the container.  You’ll need to minimize the time the fish is in the air.
  5. Identify the swim bladder location.  It may be more visible on one side than the other.  It should be a clearly visible pocket of air.

    Tilefish with Enlarged Swim Bladder

    Tilefish with Enlarged Swim Bladder

  6. Lightly dab the alcohol on the area with the Q-tip.  This will clean the area before the puncture.
  7. Holding the fish, angle the syringe toward the fish’s head at a 45 degree angle.  Insert the needle into the swim bladder, making sure to just enter the swim bladder.  Do not exit the other side of the fish or puncture other organs.

    Finding the Swim Bladder

    Finding the Swim Bladder

  8. If you are using a larger needle, then the trapped gases may exit when the needle is removed (you may have to lightly press on the swim bladder for this to occur).  However, my needle was too small, so I had to draw back on the syringe to remove the air.  Do not remove all of the air – you do not want to collapse the swim bladder.  Remove the syringe and cap for safety.

    Puncturing the Swim Bladder

    Puncturing the Swim Bladder

  9. Dab a small amount of iodine on the puncture area with the Q-tip.

    Applying Lugol's Iodine

    Applying Lugol’s Iodine

  10. Return the fish to the water.

If the procedure was performed correctly, the fish should have a much easier time swimming and will swim more level.  When the fish is first returned to the tank, it may act somewhat erratic or stressed (which is typical.)  I highly recommend using a broad spectrum antibiotic to help prevent further infection from the procedure.

Post-Procedure Recovery

Post-Procedure Recovery




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