The correct fix is to sand it down, put a layer of fiberglass cloth on it, and sand it smooth, but the easy fix it to dab it with shoe-goo or something similar to seal it up.
How bad is it, and how bad does it leak?
If it doesn't leak, you might get away with just roughing it up with 80 grit paper, and putting a smooth layer of fiberglass resin on it, just to seal it and make it smooth. Then just sand it smooth to the surrounding surfaces to reduce water drag.
So, where do you ride around the Killeen area? I am down south of Houston, and looking for freshwater locations to camp and ride.
on the bottom of my 96 GSX theres a small spot where it obviously must have been on a rock when someone sat on it in shallow water, but theres a small crack / puncture is there anything I can put over it like a sealant or filler? 
