The point is not to avoid doing something nice for someone, but if you want to donate fish, give tuna or pollack that is $2-$3/lb max. If i needed a food shelf, i would rather get 10lbs of tuna vs 1lb of freshwater fish.
Also, those fish are stocked, studied, maintained and paid for by fisherman. Unless you are fishing waters that need to have fish removed, you are depleting a resource at the expense of another fisherman for the benefit of someone who doesnt pay for it and would benefit more from a different source of protien.
I believe in helping others, but i think it is important to make sure you are doing it in the most efficient manner. Think of it this way, if you have an incredible amount of wealth and want to donate cars, do you give porsches to 10 families or give 100 fords?