Fish Emulsion as a Plant Fertilizer

Written by matt gallagher
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Fish Emulsion as a Plant Fertilizer
Fish emulsion offers one of the best organic fertilisers available. (garden image by Gina Smith from

Fish emulsion is one of the better organic plant fertilisers available. While its NPK ratings (nitrogen, phosphorus, and potassium amounts) don't pack as big a punch as other fertilisers, fish emulsion contains many micronutrients vital to plants. In addition, it contains trace elements found to be very effective against pest control, especially controlling nematodes.


Most fish emulsion comes from either the fish meal trade or the fish canning industry. The menhaden---a small, bony fish in the Atlantic Ocean and Caribbean---is harvested for its protein values to make fish emulsion. The fish is cooked and pressed for fish oil. The liquid is next centrifuged so the fish becomes soluble. That is then boiled down to a gummier fluid to become fish emulsion. Typically, a deodoriser is added. Most modern mixes have little or no odour.


Fish emulsion is typically applied in a water mixture and sprayed on by a foliar spray. It should be carefully applied so the bottle nozzle doesn't clog with solids, which can often be dragged up into the spray head.

Mix about one to four tablespoons into a gallon of water. Avoid applying it in the heat of the day, as it releases too quickly. Heat can also increase the foulness of the odour. You can often get fish emulsion in a mix with a seaweed extract, which also helps minimise the odour.


In addition to organic fish emulsion, gardeners can also opt for amended fish emulsion and enzymatic fish fertiliser.

Amended fish emulsion follows similar processes as organic, but contains synthetic materials such as urea, so it's not a completely organic fertiliser.

Enzymatic fish fertiliser is made from fish scraps placed in a stainless steel vat with added enzymes to break it down. It typically has a NPK of 2-5-3, but is not considered organic.

Timing of Application

Ideally, fish emulsion should be applied early in the season when the temperatures are still cool. That is when organic fertilisers have a slow release. It's best added in early morning or evening. Avoid full sun. Always apply with roots well watered ahead of time.


Fish emulsion contains phosphorus, nitrogen, potassium, sulphur and other trace elements. The phosphorus works to promote root development. Nitrogen encourages the production of protein. Phosphorus helps balance the pH levels.

Fish emulsion is an ideal organic fertiliser for greenhouse plants, perennial flowers or vegetables, and transplants with small root systems. It's also useful to confuse and deter some animal pests.


Do not apply an over concentrated mix of fish emulsion fertiliser, as it can burn the plants. Be especially careful with container plants.

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