Most of my fishing has been in shallowish water as well, so I have come across this only a handful of times. Fortunately for me (and the fish) on almost every occasion I was fishing with someone who had considerable experience with the technique; made it look very easy, fish all swam away strongly. The one exception was an instance where I landed a really large walleye, in the 28-inch range, from water almost 60 feet deep. She simply couldn't manage to dive when released, despite seeming very strong otherwise. My de-gassing mentor was not present; we eventually netted her again, did the deed (I used a worm inflator needle!), and carefully released her. She too swam away as though unphased by the experience of having a ham-fisted tradesman stab her abdominal cavity with a Tyrannosaur-sized needle. I've wondered about that fish ever since, hope that she made it.
When/if you hit the right spot, you will know immediately; the sound, the smell, the instant improvement in the movement of the fish. It is supremely satisfying to see it work, but it will always be an absolute last resort.
But the guy who did it regularly, on at least two occasions that I know of, actually re-caught the fish in question, one later in the same year and another several years later (!), identifying them by means of the DIY fish-tags that were once popular on the market. He kept meticulous records and quickly traced them down in his notes. So, it isn't just an old wive's tale; the technique can work, at least sometimes on at least some fish species (his were both walleyes).
If you decide to take the plunge, I would suggest careful study of bichir anatomical drawings so that you at least have a chance of hitting the right spot. And...you won't know which side is the issue, will you? If I recall correctly, only one bladder performs the breathing function? If that's correct, maybe attempt the other side first and see how that goes before attacking the "lung" later on. It seems to make sense to me that the breathing bladder, being constantly in use, is probably still working properly since the fish is still alive...so therefore perhaps the problem is more likely the other side? Dunno.
The small polys on sale locally are tempting...almost overwhelmingly so, especially the ornates...but I am working hard on maintaining my hobby involvement at a relatively low level compared to times past when it became more work than fun. I'm too old to create more work for myself; I want more fun.
thebiggerthebetter .
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