DID YOU KNOW?
You might have noticed that some fish pulled from deep water can be released and will swim right back down, but others have trouble descending. That’s because some fish (physostomous species such as trout) can “burp” air as they’re being pulled up, relieving the gas buildup in their swim bladders, while others (physoclistous species like walleyes) have no connection between the swim bladder and the gut. Conse-quently, their swim bladders ex-pand, greatly increasing their buoyancy. Eventually, gases that build up in the bladder dissipate and the fish can once again return to its deepwater haunt.