Probably not the right area, but this is as close as there is right now.

One of the secrets to doing things profitably is not to waste. My grandpa always said about butchering pigs "we use everything but the squeal".

When you fillet a fish, there are always left overs. The guts, bones, head and a little meat. One very profitable way to deal with otherwise smelly waste is to make fish emulsion. The process is pretty simple. Put the left-overs in a plastic barrel or bucket, cover with water, and add enough phosphoric acid to equal about 1-2% of the weight of the fish. The pH is supposed to stay in the 3-4 range. Kept warm the stuff will break down and you'll get oil, fish emulsion and some glop on the bottom.

The fish oil can be put to a variety of uses, including bio diesel if you have enough of it. The emulsion is neutralized with lime, filtered and bottled. It sells for up to $40 a gallon. The glop on the bottom goes into the compost for the worms. Nothing goes to waste.

My big hold up is finding food grade phosphoric acid at a reasonable price in less than tank car quantities. If anyone knows about a source, I'd be grateful.