Fertilizer, according to the Colorado State Extension, is a soil amendment that adds the minimum amount of nutrients into soil for a plant's growth. Nitrogen, phosphorus and potassium are the main three nutrients a garden needs, and fish emulsion fertilizer has all of them in small amounts. Fish emulsion is used for its high, quick-release nitrogen content. Using fish scraps from a meal or fresh fish caught out at the lake to make fertilizer are economical ways to boost your garden's production.
Place your fresh fish in a bucket and put the bucket in a cool place out of the sun.
Fill half the bucket with shredded leaves, straw or sawdust to control the odor of the decomposing fish.
Add a couple of tbsp. of epsom salts to the mix for magnesium and sodium, nutrients your plants use to grow. Add molasses to the mix as well to speed up the production of microbes and keep down the smell.
Stir the fish daily to add air to the mix. This speeds up the decomposition process. Let the paste rot for one to two weeks before adding it to your compost pile.