So how deep does a fish (mainly a bass) have to be to have its swim bladder either come out of its mouth or explode when you reel in too fast? I saw a grouper do this on a deep sea trip last year.

Joe

It can happen anytime you catch a fish deeper than about 30 fow. Except for lake trout which belch or pass air bubbles to regulate their air bladders. If you bring fish up slowly enough from deeper water it helps minimize the damage. Now gobies are not a problem as they have no air bladder. That is why they stay oriented to the bottom. 

In general heavy scale fish like fresh water black bass can not release gas pressure from their air bladders.

The surrounding water pressure on the bass keeps the gas in the bladder regulates the size of the bladder; more water pressure the bladder compresses, less water pressure the bladder expands. The keeps it's bladder filled with enough gas pressure to maintain neutral balance so it can suspend with little effort at what ever depth the bass is acclaimated to. It takes about 24 hours for a bass to add or reduce gas pressure in the air bladder. It really doesn't matter if the bass is brought up fast or slow, the bladder expands to the same size.

2 atmospheres or about 30' depth change is within a basses comfort range.

The over expanded bladder is usually result of 40' or more depth change. You may hook a bass at 30' bring it and the bass rolls over due to over expanded air bladder because that bass was acclaimated to 45' swim up to 30' to feed, you hook it and the total depth change was 45'. This happens often in deep clear structured lakes at night or during the cold water periods.

Fast pressure changes may have a major impact of brain function and there are studies ongoing in that problem, a different topic.

Tom

Wow! Lots of info WRB. Thanks! There really is a science to the swim bladder stuff. I'm looking up some web info too. :-)

I figured I'd chime in, as I did a report for school on class osteictheyses (bony fish) with some good info on swim bladders but WRB already hit the nail on the head!