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How to Use Fish Waste Fertilizer

Fish parts, such as guts, bones and heads, are rich in nitrogen, potassium, phosphorus and trace minerals that support root and foliar growth as well as healthy, abundant blooms. Liquid fish emulsion, which is sold in stores as an organic fertilizer, is made from fish parts not used by processing plants. Regardless of its form, using fish waste in the garden is as easy as burying leftovers from a catch or from a fish dinner in the soil or compost heap.

Fish Emulsion

Dilute liquid fish emulsion before using it on plants. To water individual trees, plants or potted plants, use a tablespoon of emulsion per gallon of water. For a foliar spray, mix 1 or 2 ounces of fish emulsion into a gallon of water and spray it onto leaves or grass. Apply in morning or evening when temperatures are cooler.

Feed sensitive and hot weather seedlings, such as tomatoes and peppers, with a teaspoon of undiluted fish emulsion when you transplant them. This helps protect roots and give them a nutrient boost. Apply to more mature growth in the spring as well when their growth is more active.

Make your own fish emulsion by boiling leftover fish parts in a large pot with just enough water to cover the waste. Liquidize it in a blender, and use this mixture as you would commercial fish emulsion.

Use Fish Waste

Bury fish guts, heads and other parts in the garden near plants or trees that need an extra nutrient boost. Place the fish waste at least a foot below the soil to discourage wildlife and pets from digging it up and try to avoid disturbing the root system.

Bury a dead aquarium fish in a houseplant instead of flushing it down the toilet. Make sure the plant is out of reach of other house pets.

Compost fish waste in an outdoor compost heap by burying the fish at least two feet deep in the compost pile. However, you can not disturb the fish waste, so this option is not for compost heaps that require regular aeration. This method works well for a small amount of fish waste. For larger amounts, turn the fish waste into a liquid fish emulsion. (see Section I)

Use fish waste water as a nutrient-rich fertilizer. Water plants with waste water from freshwater aquarium and fish pond water changes or water you’ve used to wash fish while cleaning them.


Fish fertilizer and fish emulsion are strong-smelling when first applied, but the odor will fade in a couple of days.


Make sure that dogs don’t eat raw fish buried in the garden or soil that has been watered with rinsings from cleaning fish. This can cause salmon poisoning, which can be toxic to dogs.

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