Polarized lenses help visibility mostly by filtering out reflected light from the surface of the water, which is much more common in the daytime due to the light source (sun) coming from a different direction than your field of vision.
If you are bow fishing at night using a boat with lights or a headlamp, MOST of the effects of glare are negated by the light shining from your position towards the fish, such that the glare reflects away from you. There is usually still a minor amount of glare that still comes back at you, however, due to surface ripples.
The above might not be true, however, if you were shooting below some artificial lights such as streetlights on the back of a parking lot, dock lights, etc. In that case, polarized glasses might actually help more than you'd expect.
I have a set of cheap polarized sunglasses that I bought without realizing that the tint on them is not aggressive enough for my light-sensitive eyes. I bought them at BPS for about 15-20 bucks, and still use them on occasion when fishing in low light or on cloudier days. You might decide it's worth experimenting with something like that to see if it makes a difference in your situation, especially if you are seeing glare on the water where you are shooting. I wouldn't dream of buying a set of Costas for trying to bowfish at night, though :)
See if you can find some polarized, low-tint (smoke lens, maybe?) glasses on the internet and give those a try! You might be on to something :)
