Don't ask me, I'm asking you Mr. Great White Buffalo! can you tell me what they're doing when they gulp air??? by capillary fed does that mean they can transfer air (or just the o2?) to the swim bladder from only the gills/blood, or can it also come from the gut ?? just curious. I'm surprised fish geeks Pete and John C. aren't here to help out yet.
Just in case there are dorks among us (aside from me), I found this useful info on the web:
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The gray snakey thing is the esophagus; the blue thing is the swim bladder, and the red is a blood vessel.
Not all fish have the exact same anatomy. The term fish isn’t even a scientific one. Not all the internal organs are present in all species. Not all swim bladders are identical, and some fish species don’t even have a swim bladder. But generally, there are two types to be found in fish that do posses this fascinating organ, open and closed. The open swim bladder is connected to the esophagus (the canal which connects the throat to the stomach) and this gives fish the ability to gulp air and so adjust their buoyancy. The air is stored in the swim bladder in order to counteract the force of gravity and to give the fish neutral buoyancy, or something to close to neutral buoyancy. Many fish will sink if they stop swimming because they have less than neutral buoyancy. It is the movement and shape of their fins that keeps them from stalling in the water and slowly sinking to the bottom. Many sharks have this problem. They have to keep moving or they stall and sink. The natural world is full of similar imperfections.
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” />Fish with the second type of swim bladder, the closed type, do not require gulps of air from the atmosphere to adjust their buoyancy. Their anatomy is slightly different. In the closed type the swim bladder is not linked to the esophagus. Instead, it is connected to the bloodstream by a a gas gland which allows oxygen, carbon dioxide, and nitrogen to enter or exit the swim bladder. As a result fish that posses this type of swim bladder don’t require access to the surface and therefore can enjoy a wider range of habitat such as the deep sea. Although, there is a downside to this arrangement; adjustments to the gas level in the swim bladder takes longer than in the previously mentioned open type. This is illustrated by the fact that when some deep water fish are brought to the surface too quickly they expand and burst forth their internal organs because they cannot compensate for the sudden change in pressure. Certainly, in aquarium fish it is not unreasonable to consider the possibility that there are diseases that might affect the gas exchange between the blood and the swim bladder.
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I've not yet discovered if a muskie's swim bladder is of the open or closed type.
No question esocids have an open swim bladder.
All esociforms can survive in low-oxygen waters and are probably capable of breathing air. Umbra can reportedly survive significant periods out of water. Esox and Umbra have well developed swim bladders adapted for air-breathing. Dallia, oddly enough, has adapted its esophagus to perform the same function. Crawford (1974).
Also from my observations…
If you can "burp" a muskie it has to be an open swim bladder. I've also watched fish burp themselves when coming up to the boat following a lure from down deep.
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