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Fish Emulsion as a Fertilizer

organic tomatoes with organic label in clear focus image by Paul Hill from

Fish emulsion is a natural organic fertilizer that is often higher in nitrogen than in some other nutrients. Although not a high nitrogen fertilizer, it adds more nitrogen and can, as a result, be good for green, leafy plants. However, its balance of nutrients is good for almost any growing plant, including vegetables and flowers.

What is it?

Fish emulsion is made by letting fish scraps rot in warm water for several months. As the water evaporates and the fish scraps decompose, the emulsion becomes thicker. The amount of time it steeps depends on the desired concentration of the emulsion. After it has steeped, the solids are strained out, and the resulting liquid is diluted and used as a fertilizer. Some fish emulsions are concentrated to the point that they become more like a gelatinous paste. These types of emulsions usually need more dilution than fully liquid emulsions.


All fish emulsion needs to be diluted before it is applied to a plant or garden. The level of dilution will depend on the brand of emulsion. If you are making your own emulsion, try a 1:4 dilution for a fairly thin emulsion. In some cases, thick emulsion pastes are diluted at a rate of 1 tbsp. per gallon. If you have trouble getting the paste to mix with the water, try mixing it with a cup of hot water. The hot water melts the solids. Once diluted, let your paste-based emulsion sit for a couple of hours before use to ensure it is mixed well.


Most commercial fish emulsions are 5-1-1 or 5-2-2 fertilizers. That means that they are 5 percent nitrogen and 1 or 2 percent phosphorous and potassium. Fish emulsions often also contain trace minerals and other organic nutrients that are beneficial to your plants.

Augmenting Fish Emulsion

Many people use a combination of fish emulsion and kelp emulsion, which provides many more trace elements without affecting the nitrogen-phosphorous-potassium balance of the fish emulsion. Fish and kelp emulsion are often sold next to each other at many garden centers.

Advantages Over Other Fertilizers

Because it is a liquid fertilizer, diluted fish emulsion moves quickly down through the soil where it is broken up by micro-organisms into forms usable by your plants. Powdered organic fertilizers must first mix with water and move through the soil. Because fish emulsion penetrates the soil more quickly, its nutrients are available more quickly to your plants.

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