Venting and releasing fish with Barotrauma

Releasing fish with barotrauma

With the popularity of catch and release fishing, questions are often raised about the best way to release fish with barotrauma.

When fish are brought to the surface quickly from depth, gas in the swim bladder can expand and not have time to vent naturally, resulting in a bloated appearance and preventing fish from returning to a comfortable depth.

In severe cases the pressure can push the stomach into the fishes mouth, cause the intestines to protrude from the anus and even rupture the swim bladder.

If not corrected, the fish can die from  a number of causes; damage to the internal organs, easy target for predators, floating and exposure to the elements.

Obviously this defeats the purpose of fishery management laws such as minimum size limits and daily catch restrictions.

There are three primary ways to arrest the symptoms of barotrauma and give the fish a good chance of survival.

  1. Release Weights
  2. Release cage
  3. Venting

It does however depend on the fish species (some are more susceptible than others) and the depth they are caught.

For example, fingermark suffer severe and fatal barotrauma if caught in waters greater than 10 metres in depth. You can view the effects of barotrauma on fingermark in this video by NT Govt.

This video by Queensland Fisheries explains all three;

Release Weights

In Western Australia it is mandatory in the West Coast Bio region to carry a release weight on board when fishing for demersal species.

A release weight consists of a lead weight attached to a barbless hook to assist the fish return back to the bottom.

A few jigs on the weight and the hook will bounce out of the fish releasing it at depth.

Release Cage

A release cage is a bottomless wire cage placed over the floating fish. The cage is weighted and pushes the fish to the bottom. Once stabilized, the fish can swim out of the cage.

We have never tried a release cage and while watching the Fisheries Qld video, looks like it may be a calm water only proposition.

Venting with a needle

In our previous post on impoundment barra techniques, Ryan mentioned using a bone marrow remover for venting fish and demonstrates the technique in the video below;

He was given the tool by a medical practitioner many years ago although we have managed to find a similar tool, the T-handle Jamshidi, however at this point the supplier does not sell to the general public.

They are called a “bone marrow aspiration needle” for those that want to google further.

Here is the one we use.

Bone marrow aspiration needle for barotrauma venting

In Florida, venting was compulsory until 2014, so there are a number of devices available, called venting tools. We haven't used any of them so we cannot recommend, however here are some of the ones we found:

Vent Right Venting Tool

Suntaggers Venting Tool

Obviously not all fish need to be vented, and if the need arises, it's best to do so as quickly as possible to reduce further harm.

There is no need to puncture the organs protruding from the fish (stomach and intestines) as these will return to their usual size within 2-3 hours after venting the swim bladder, behind the dorsal fin as shown in the videos.

To eliminate the problem entirely, we also recommend (once you've caught what you need for a feed) moving to shallower water if wanting to continue with catch and release.

Have you ever tried venting a fish?

Or perhaps you prefer one of the other methods?

We'd love to hear your thoughts so please go ahead and comment below.


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About The Author

Ryan Moody

Ryan Moody started his fishing career on the reef boats before catching bucket list marlin for the likes of champion heavy tackle angler Johnno Johnson, INXS and the King of Sweden. Branching out in the late 80's to guided barramundi fishing, Ryan has made a name for himself as a Big Barramundi specialist and to date has put clients onto over 2000 metre plus barra. That is over 2 kilometres of metre plus barra! With attitudes changing from 'keep all you can' towards catch and release, Ryan has decided to share his extensive knowledge and hopefully inspire people of all ages to get out from behind the computer screen/TV and into the fishing outdoors lifestyle he has spent his life perfecting.

Facebook comments


  • John

    Reply Reply February 16, 2019

    The venting tools needle from tackle shops fits onto large syringes Push plunger down insert needle to recommend area and draw plunger back Repeat if needed by disconnecting syringe but leaving needle in air bladder You can physical ly feel and See the bloated area shrinking

  • Scott Meyer

    Reply Reply May 6, 2017

    I understand why Paul is skeptical or long-term survival. The barotrauma symptoms he documented have been documented also in Pacific rockfish in North America. Survival of rockfish released using release weights has also been documented consistently. Short-term survival (2-17 days) of over 90%, and longer term survival (1-2 years) of at least 65% have been documented. The healing of ruptured swim bladders and recovery of visual impairments from pop-eye (exophthalmia) and air bubbles (corneal emphysemas) have also been documented. One study found no effect on female reproduction. Most of the work is in the scientific literature, but there are many summaries on the web.

    I would recommend NOT puncturing a protruding stomach. It is protruding because the swim bladder is extremely inflated and has pushed it inside-out, or because the swim bladder has ruptured and the trapped air has pushed it out. Poking a hole in the stomach lining will release the gas, but also open the body cavity to infection from stomach contents. Sending the fish back to the depth of capture with the release weight will shrink the gas volume and the stomach (and eyes) will return to normal position. No need to do additional damage.

    • Ryan Moody

      Reply Reply May 7, 2017

      For sure Scott we agree and that is also what is recommended by fisheries. Now we have the big boat and are heading offshore more often, we will endeavour to demonstrate the use of a release weight.

  • Paul

    Reply Reply April 10, 2017

    When a fish suffers from barotrauma there is a lot more than swim bladder damage related the the fish.
    The swim bladder is obvious as it is what we see.
    Fish suffering these effects have a low survival rate.
    I myself don’t believe any of these methods work successfully.
    At first impression yes, but in the near future no.
    Other symptoms of barotrauma include hemoraging of the eyes, cornea, perforations of the swim bladder, displacement of the stomach and intestines, liver tissue trauma, damage to the veins which connect the liver to the heart, bile leaking from the gale bladder to the liver, enlarged and ruptured spleen and stretched and ruptured veins that I am aware of.
    This information I found through NT fisheries.
    When fishing for particular species when we bag out we move on to try to find marks where other species may be or move to grounds less than 10 meters deep wher the fish do not suffer from these effects.
    I also believe lower size limits on effected fish is a good thing so less get thrown back before someone fishing moves on.
    I also take minimal bait with me now and when I catch bycatch suffering barotrauma dong them on the head and use them for bait rather than throwing them back to die a painful death, good bait to and saves money.
    Excess I cook up and feed to my dogs if they are fish I don’t like. Good for them and saves money again.
    I have also attached a link on barotrauma and golden snapper.
    Sorry for the long winded email but I think people who fish for a sport and care about it should know


  • Howard

    Reply Reply April 6, 2017

    Hi Ryan
    I’m glad you have addressed this issue however I am sure I have killed a number of fish trying to deflate them by venting.
    After reading the information on the site below, I made myself a 16 ounce release weight and have been successfully using it for undersized and unwanted reef fish.

    This site has some other good info on it despite coming from NSW!

    • Ryan Moody

      Reply Reply April 10, 2017

      Thanks for the comment and link Howard. Release weights are certainly a good option. Cheers

  • Julian

    Reply Reply April 3, 2017

    G’day Ryan, if a fish’s swim bladder is protruding from the mouth, I have been “popping” it with the hook tip. I’ve noticed these fish then swim away very strongly, and I assume that a tiny prick wouldn’t take long to heal.
    Do you think this method is advisable?

    • Ryan Moody

      Reply Reply April 10, 2017

      Hi Julian, the video from Qld fisheries recommends one of the three methods outlined in our blog, however if you watch from 4:28 it explains how Snapper and Pearl Perch have a 90% survival rate if treated and caught in less than 20m water and that often the bladder bursts on ascent so they don’t display symptoms. Yet the bladders heal in 2-3 days. So I guess it depends on the species as some species like Fingermark and Teraglin Jew are particularly susceptible. What is hanging out the mouth is the stomach and it is not recommended to pop it. We prefer to vent from the side as it deflates the swim bladder and gives the bladder something to press against while healing.

  • Levko Yaskewych

    Reply Reply March 23, 2017


    I have been on some fishing trips and the statements made to me about most fish brought from depths is that the survival rate is extremely low.

    What species have you observed that can survive the trauma and be released with HIGH rates of success?

    Should the fishing in deep waters have restrictions for this reason? Should this mean commercial nets should be totally banned as they would mass kill everything from these depths regardless of the fish being eaten or not?

    • Karen Rudkin-Moody

      Reply Reply April 2, 2017

      Hi Levko, It really does depend on the species and how quickly they are brought to the surface. Of course, long term survival rates are a bit hard to quantify as we don’t follow the fish for days to find out. Commercial nets are unlikely to be totally banned as many people eat fish and there are no other efficient ways to catch them. Typically it takes time for the net to be hauled up and this reduces barotrauma (a bit like a diver takes makes a slow ascent to avoid the bends). Also some fish are less susceptible to it. This is why we recommend fishing the deeper water first for the fish to take home, and moving to shallower water if you want to continue fishing catch and release.

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