Over the years I have caught many fish from water deeper than about ninety feet that come to the surface with their stomach protruding from their mouth like a big balloon. Not doing my research, I though it was an air bladder, and while I knew it had to be vented, I never really studied the best way to accomplish the task.

From a Professional

One of our readers, Nichola, from the Atlantic States Marine Fisheries Commission, sent me some information on venting that has changed the way I handle these types of fish.

One thing I do not do now is poke a hole in what I thought was the air bladder (swim bladder) protruding from the fish?s mouth. That is not an air bladder; it turns out it is the fish?s stomach being pushed out because the swim bladder has burst.

How the Air Bladder Works

Swim bladders are a closed organ in a fish?s abdominal cavity. Containing gasses, it is regulated by the fish to allow it to remain at a constant depth. As the fish moves shallower, outside pressure on the fish reduces and the fish compensates by adjusting its air bladder. The reverse is true as the fish moves deeper. Some fish are able to make faster adjustments to their swim bladder than others, but despite that ability, they still have issues of they are brought to the surface too quickly from deep water.

The Problem

The problem occurs when a fish is brought to the surface too quickly, unable to keep up with the pressure change. The air bladder actually bursts inside the fish allowing those gasses to fill the abdominal cavity, and often pushing the stomach out of the mouth.

The proper thing to do is vent the abdominal cavity, not poke a hole in the fish?s stomach. It turns out that the air bladder will heal if vented properly.

Big Fish in Trouble

In the winter time, some fish that normally inhabit shallow water will migrate offshore to deeper water. This is particularly true of the redfish ? red drum. They cannot regulate their swim bladder as well as the native deep water fish. Consequently, when some of these giant reds come to the surface too quickly, their air bladder bursts about half way up, pushing their stomach into their throat and floating them to the surface like some giant cork.

Take Heed

Every angler needs to pay particular attention to these giant red drum. These are the big brood stock. Over a wreck or reef in water deeper than about fifty feet, these big reds can sometimes be caught one after another. My practice, when I find a reef covered with reds, is to move to another location. The mortality, while lower when we vent them properly, is still high on fish like these.

Need More Information?

For an in-depth look at how and when to vent a fish, go to the Sea Grant Florida website page at http://www.flseagrant.org/program_areas/fisheries/venting. There is even a video on the page that shows you just how to properly vent a fish. Interestingly, there is now a company that makes a tool specifically designed for fish venting. Mine is on order at this writing!