I have a question about this. I noticed that there are specific bows for doing this or at least Cabala's has specific bows but I wonder if you can alter a regular compound bow.
You really just need some way to reliably feed out the string as the arrow is cast. I've seen natives use one of the 8-12oz coke bottles as a spool/reel. Just pinch it in the bow hand between the middle and ring fingers.
Most of the "special" bows are made of either entirely waterproofed materials, so getting wet doesn't cause issues, or is a non-compound, so that you can get reasonable power from a half draw/snap shot technique that is used in some places. When I first heard of bow fishing, I read about it in an article talking about Depression era fishing in the Appalachia area. Fellas up that way used cedar slats (rot resistant) that they would string, and submerge (!) before shooting. The water is shallow and crystal clear in those parts, and the waterways not very wide, and they would wade along looking for fish. Instead of a lined gig, they made the arrows out of dried cane. By leaving the nocks intact, they acted like a bobber, and the fish would rise to the surface, kind of like jug fishing. I, personally, would research into the Indian tribes in your AO, and see how they fished. Most of the time, it's too effective to be legal, but sometimes you get a gem.
Bow fishing is easy, and fun. I did it as a kid, but it is hell on "catch and release". You can use any bow you like, it is the arrows that are different. Most are fiberglass, though i started with cedar, and fixed spear points. Most now are detachable tips, and the line stays in the tip, and the shaft floats. (Though not all do) You can buy a reel that screws right into the stabilizer mount, or mount a standard reel to a scred in stubby rod made for the purpose. Or use a float and just unwind the line to flow freely. (Line in contact with the water will drag alot, but looped over a straightened finger will fly just fine, however, a kink in the line can grab your finger. You are shooting short distance, and refraction will throw off your aim, so practice with a submerged target. Floating inverted targets are easy to make. If you like a challenge, crossbows and compounds WILL fire under water for spear fishing with a snorkel.