<a href=showthread.php?s=&postid=12022130#post12022130 target=_blank>Originally posted</a> by cl2ysta1
think of it this way. the fish have to put so much air in their swim bladders when they are deep in the water. if you had a balloon with so much water, and put it way down in the water the pressure of the water would push on the sides. so these fish fill up with more air than they would need at lower depths. WHen they are brought up to the shallow depths. they have all this air fromt eh pressure and it expands b/c there is less pressure. We have this happen often will walleye and sheephead we caught for an aquarium i worked at. Some fish can burp the air up *catfish etc* these fish cannot. soooooo you have to do something called "fizz" the fish. Basically you stick a needle from a syringe in the fish under water. the swimbladder will fizz. This releases the excess air for them and allow them to swim normally. this heals up what seem slike almost immedietly and if the needle is clean and this is done in the correct spot we've never lost a fish to it. we have however lost fish to NOT fizzing them. you have to have a knowledge however as to where the swimbladder is located on different species of fish or you risk puncturing internal organs