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Fish Waste – A 5 Minute Tutorial

Fish waste is an underutilized form of food waste that has potential for a wide array of products, including methane production. In Norway alone, over a million tonnes of it is generated every year.

Image shows the features of fish waste.For a long while, fish waste has been refined using comminution and heating, to separate the fish oil. Quality fish oils have a good market value, but the market size is limited.

Reduction in the Dumping of Unwanted Caught Fish

Image illustrates the fish waste tutorial.

Dumping it at sea is increasingly being outlawed, so the tonnages which are landed at ports are rising. The result is that there is more and more of this waste type which needs to be found a use!

Fish waste was once historically discharged back into the sea routinely, during the processing of the catch. Today the discharge of this waste is coming under increased scrutiny in fish quota regulations globally. The EU has already implemented regulations against doing it. If it is not discharged while at sea, transporting untreated waste takes up valuable cargo space on board the vessel.

Therefore, there is an abundance of fish waste. This means that it can be a potentially valuable resource, from which high-value products can be obtained. It’ a great source of minerals, proteins and fat. It’s also, a rich source of proteins that can be utilized as low cost substrates for microbial enzyme production. Plus, it has long been known to be a useful soil amendment, a natural source of nitrogen.

Value of this Waste

Fish waste has been found to contain essential nutrients like nitrogen, potassium, phosphorus, calcium, magnesium etc. and the anaerobic digestion process can be used to ferment it in biogas plants. These produce a gas with about 60% methane content. Lately, it has been comprehensively tested and found to have good energy potential.

Fish Waste Uses

Although fermented fish waste has growth promoting nutrients, it is important to assess its feasibility as fertilizer as imbalance in nutrient content can lead to uneven plant growth, and reduce the yields. Nevertheless, the converted output has the potential for use as liquid fertilizer, although the low NPK-level is a concern.

It can also be composted. When composting such waste as fish parts, it is mixed with plant waste like:

  • wood chips,
  • leaves,
  • bark,
  • branches,
  • peat, or even
  • sawdust.

The development of newer technologies to utilize fish waste has fostered use of “bioactive value-added products”, for specific health benefits.

The fact that fish waste can cause big problems for the environment is evidenced by Tara Martich. In this respect, its management has been difficult in areas like the Aroor industrial belt, and the Kochi Corporation. In one area, the discharged fishy-waste has piled up underwater into a massive carpet of gelatinous goo. It’s a “goo” that suffocates sea-life and disrupts the entire ecosystem in that area, said Tara, a permit coordinator with the EPA.

Utilization Research

In recent years potential use of this fish waste has become a popular research topic. One favourite topic for research is how to best use it in anaerobic digestion plants, with the primary intent to create energy from the biogas produced. The process would work especially well where it has so far simply been thrown away and where energy generation is poor, and prices high. The AD process would work especially well where fish waste has so far simply been thrown away, and where energy availability is poor.

However, in general, and just like any material which is more abundant than the market to use it. Fish waste has little or no value, but it must be disposed of responsibly. If left to decay can cause many human-health and environmental-pollution problems.


On the Isle of Lewis, salmon waste was both becoming a disposal problem for their landfill. The community also operate an anaerobic digestion plant at their CREED recycling facility. They also knew it would work better, and generate more electricity, if fed daily with ensiled fish waste.

How they found suitable reliable equipment to feed fish waste into their digester. And, how also they coped with the need to pasteurize the fish waste, and find the funding to use it, makes a fascinating story.

Read about the Landia Pasteurizer that has been vital for Fish Waste Treatment in Scotland by clicking here.

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