What fish and parts of the fish are used for making fish fertilizer? By-products or waste materials from various types of fish are used. And although technically several varieties of fish can be used, mostly Menhaden fish that contain few amounts of meat and used for making animal feed are used.

The first step is to cook the fish and to squeeze its juice and oils by pressing. The oil is removed while the leftover solids can be ground and baked into protein meals and fed to animals. The juice of the fish is brought to a boil until it becomes more concentrated and results in a fish emulsion.

A small amount of phosphoric acid is added to the fish emulsion to lower the pH. Lowering the pH makes the liquid fertilizer more acidic, which prevents it from decaying and fermenting into gas. Before phosphoric acid was added in the manufacturing process, containers of fish emulsion were known to burst from fermentation. Because the amount of added phosphoric acid is so small (less than one percent by weight), the product is still considered organic.

Standard composition of organic fish emulsion fertilizers is about 5% Nitrogen, 2% Phosphorous, and 2% Potassium. It also contains micronutrients that are vital for promoting plant growth.

Depending on their proximity to the sea or fish waste sources, many organic growers are daring enough to make their own fish fertilizer emulsions to cut down costs.

Many organic fertilizers are slow acting. Not fish emulsion. The nutrients in fish emulsion are released almost immediately. That’s why it is particularly good for seedlings and transplants–it gives them a jumpstart. Gardeners either water the diluted liquid fertilizer into the soil or spray their plants for a foliar feed.

Fish emulsion is a fairly mild liquid fertilizer, but it can burn if applied too strong, so it’s important to follow mixing directions. It has a definite fishy odor, but the odor goes away in a day or two after application. Some manufacturers add a deodorizer to their products. Fish emulsion must be used when it’s mixed; it can’t be stored after it is diluted. By the way, the undiluted liquid must be stored at room temperature because it degrades if it gets too hot.

Once again, we need to repeat that organic growers need not worry that fish emulsion fertilizer is depleting our oceans of the important Menhaden fish or other fish that people need for food. Fish emulsion if primarily made from fish waste of the established animal feed and fish oil industries, which would have been dumped in landfills if not used. The organic label in fish emulsion fertilizers not only means natural, it also means environmentally safe.