Scientific studies have shown that species with large swim bladders benefit from venting if they are to be released. After reeling in a fish from deep depths or a wreck, closely observe its condition. If the fish is bloated and floats (is unable to control its buoyancy) or if the fish's stomach is sticking out of the mouth, the fish should be vented. If the fish appears normal, not bloated, and is able to swim down to habitat depth on its own, venting is not necessary.
Venting Procedure
It is best to vent the fish as quickly as possible with a minimum of handling. If the fish's stomach is everted out of the fish's mouth, do not attempt to push it back into the fish's body. Expelling the swim bladder gases will allow the stomach to return to its normal position within a few hours. Hold the fish gently but firmly on its side and insert the venting tool at a 45-degree angle between the fish scales, approximately one to two inches back from the base of the pectoral fin. Only insert the tool deep enough to release the gases - do not skewer the fish. If a fish is extremely bloated, use the hand, holding the fish to exert gentle pressure on the fish's abdomen to aid deflation.
Keep a good grip on the venting tool during the entire process, so that an unexpected jerk from the fish does not dislodge the tool and cause injury to others. It's best to ask your parent for help.
