Light for spotting fish

I am not looking for a specific flashlight, but I would like to know what type of light I need to see fish in shallow water while standing in a boat. The light will be about 4 feet above the water and I would like to see out 15-25 feet. Should I try incandescent or LED? Should I use a filter or colored lens? I tried a P.O.B. spotlight, but it does not seem to penetrate the water.

Light will penetrate both water and air similarly. If you start with a light that throws well in the atmosphere is should also throw well through other semi-transparent media, like water, as well. Since the POB spotlight is quite a "thrower" I'm surprised that it didn't work better for you. That stated, there may be two things working against you. These are the narrow beam and the rather cool 6000-6500K (Kelvin) color temperature. It's possible that going to a 4200K class (much warmer color temperature) HID spotlight could improve the situation. It's also possible that a slightly wider beam could help as well, depending on the size and the depth of the fish. I think you've got the right idea using as many lumens as practically possible and I don't believe that any normally available LED lights are going to do any better that what you're trying now. If you had a dive rated, high output LED or HID that could be lowered underneath the water's surface, that would be something to try as also. The only problem with that is that most dive rated lights get very expensive and are often used for underwater photography. On the "cheap" you could borrow a 100 watt 12V incandescent, cigarette lighter, plug-in style, spotlight just to see if it's any better than the POB. I hope this gives you some ideas. Good luck.

I used a green kl3 while pier fishing at night. seem to work better than white.

Dang, typed a long post and the computer messed up. Thanks for the replies.

Some people mount lights directly on the bow for bowfishing at night.
Here's the commercial product:
http://tarponowski.fatcow.com/STABALIGHT.html
Some people make their own with this light:
http://www.walmart.com/catalog/product.do?product_id=13029915

The Coleman has a tactical switch which causes problems with mounting. Is there a comparable light in performance and price with a remote or side mounted switch? It would be nice if it had a six hour run time.

Instead of spotting fish, how about lights to attract fish?