Feed will always be cheaper in the long run if you're trying to push the envelope as far as the biomass in your pond.
Are you there enough to feed train them by hand?
75 fish, and you want to add 5 pounds per year per fish, that's 750 pounds of feed per year, if that's all they ate....so I'll bet it's more like 400 pounds of feed, which you could probably get for around 200 bucks.
That's cheap compared to stocking fish, I think.
