Fish die. Whether it is through disease or adverse weather, or even bad luck. Either way, it is very important to have the right tools/technology to dispose of the unusable stock appropriately. In the best circumstances this waste can then be used or recycled to become aquaculture feed and sold on.

Zero waste – aquaculture animal by-products: The Scottish Government website talks about the disposal of dead fish and aquatic animal by-products (ABPs), describing them as covered by the Animal By-products (Enforcement) (Scotland) Regulations 2013. "Any business generating material of aquatic origin which is not intended for human consumption needs to be aware of how these regulations apply to their business" they explain.

They reference three categories of aquatic ABP; Category 1 (few aquatic animals would fall into this category) "Aquatic animals containing certain prohibited substances above specified levels or unacceptable levels of environmental contaminants (for example fish contaminated with fuel from an oil spill or fed contaminated feed)".

Category 2 (mortalities would fall into this category) "Fish or aquatic animals which die from a notifiable disease - such as infectious salmon anaemia (ISA), Aquatic animal products containing unacceptable levels of residues of veterinary drugs and higher than specified minimum levels of certain contaminants, fish or parts of fish that die, other than being slaughtered for human consumption, including fish killed for disease control purposes. This includes all mortalities occurring during the production cycle in aquaculture, including fish that die from disease, third country imports that fail to comply with veterinary requirements for their importation into the community" and;

Category 3 (processing waste would fall into this category) "Carcasses (heads, frames) and parts of slaughtered fish, which are fit for human consumption but are not intended for human consumption for commercial reasons, carcasses and parts of slaughtered fish, which are unfit for human consumption, but derive from carcasses that are fit for human consumption i.e. viscera; internal organs containing parasites, carcases and parts of carcases of slaughtered fish, which are rejected as unfit for human consumption, but which do not show signs of disease communicable to humans or animals, fish or other sea animals, except sea mammals, caught in open sea for the purposes of fishmeal production or bait, by-products from fish plants manufacturing fish products for human consumption and shells from shellfish that contain soft tissue or flesh."

Where the product is made up of more than one category, the highest category applies (category 1 being the highest).

Disposal methods

Retailers, distributors or manufacturers can send up to 20 kg of raw or partially cooked fish or shellfish to landfill every week; this is a weekly limit not an average limit over a number of weeks.

Although allowed, this method is not particularly friendly for the environment, not to mention imagining what that would smell like!


Whilst at Aquaculture UK 2018, there were many methods of waste disposal on show, including an animal incinerator by "International Leaders of Incineration Solution" Addfield. Based in the UK, Addfield have over 35 years" experience designing and manufacturing solutions for all solid waste management needs. At the show the company had a miniature model of a "Thunder 1000 (1000kg)", an aquaculture incinerator. Other models available include; fish farm, fish wholesalers, marine and large fish.

As you can see in the photo it has a very basic but efficient design with a compartment for the waste of which are sold in a number of different tonnage capabilities, including; 250kg, 350kg, 500kg, 750kg, 1300kg and 2000kg, as well as a smoke chute to release the fumes.

Using an incinerator means that you are able to dispose of fallen stock quickly and with controlled access to your grounds. Using this method is considered especially sustainable as it does not leave a surplus in waste once the fish have been destroyed; it probably smells better than it does in landfill you would imagine also.

Disposing of fish in this manner (which is not necessarily possible with a grinding machine and this article will go into shortly) also means that you destroy disease. Eliminating a lot of the risk of the possibility of spreading disease, which may have killed the stock in the first place.

This range of marine waste incinerators are all DEFRA approved, comply with EU Animal By-products Regulation, (EC) No 142/2011 and pass international standards. The machines are portable, and purpose built for aquaculture. They include many additional features, ensuring extended durability, and an ability to cope with harsh environments, the company describes them as "extremely robust and built to last".


On display at the exhibition in Aviemore, Scotland was a RedUnit machine, as displayed by Vogelsang, manufacturers of pumps, maceration, spreading and biogas technology, supplying technology to a number of industries including aquaculture and agriculture.

The RedUnit is the grinding and pumping combination from Vogelsang. It has many different advantages compared to the separate products, e.g. its compact design and low electricity consumption.

"With our engineering department we design every RedUnit industrial grinder specifically customised to the needs of every customer and his specific application. It is developed as a complete engineering unit, including an advanced control system to maximise the efficiency of the complete system. The industrial grinder can be produced in stainless steel for demanding applications." Vogelsang explain.

The RedUnit offers a high availability thanks to the quick and easy concept of its individual components: the grinder XRipper XRL, the RotaCut RCX macerator, a progressive cavity pump of the CC series and/or a rotary lobe pump of the VX series.

The RotaCut, is a cutter with an integrated heavy material separator and can be used in a wide range of industrial applications. This cutter offers direct contact between the blades and cutting screen, which allows it to deliver defined cutting performance, which is a major advantage for processing fibrous materials.

Moreover, as it simultaneously homogenises the medium, it offers much more than merely pump protection for downstream systems. Medium that has been disintegrated in this manner an also be easily used in additional processes.

In industrial applications, it is usually used together with other Vogelsang products, such as rotary lobe pumps, progressive cavity pumps or other cutters, such as the XRipper.

For example, in applications involving food wastes, not all materials are suitable for being pumped onward directly after an initial shredding step. Fish, meat and vegetable waste, in particular, often contain coarse fibrous materials that are separated in a heavy material separator.

Two RotaCut models in particular have proven themselves effective in industrial applications: The RotaCut RCX is used in abattoirs as part of the RedUnit in order to meet the requirements of the EU directive on hygiene. Thanks to its compact design and reliable shredding performance, the RotaCut MXL is used on tankers to protect the pumps from foreign matter.

The benefit of grinding fish matter means that the resulting product can be made into a number of different things, including organic fertilisers/soil improvers or processing it if not spoiled to make feed or petfood for animals and farmed fish.


Aquaculture is lucky in that as an industry it has so many smart innovators out coming up with solutions that you didn"t even know you needed.

So whether you choose incineration or grinding or nothing inbetween it is a fundamental part of the production process of fish farming and aquaculture, like the western worlds toilet and sanitation system, disposing of your waste properly is not a choice – it"s a necessity.

You can find out more about aquatic ABP here:

The three ABP categorys:

Individual disposal methods

Referring to the Scottish Government mandated ways of appropriately disposing of aquatic ABP, each of the previous categories mentioned can be processed in a number of different ways.

Category 1:

• Incineration or co-incineration at an ABP approved plant;

• Pressure sterilisation;

• Using them as fuel for combustion at an ABP approved combustion plant.

Category 2:

• Incineration or co-incineration at an ABP approved plant;

• Pressure sterilisation;

• Using them as fuel for combustion at an ABP approved combustion plant.

Category 3:

• Incineration or co-incineration;

• Sending them to landfill after they have been processed;

• Processing them, if they are not decomposed or spoiled, and using them to make feed for farm animals;

• Processing them and using them to make petfood;

• Processing them and using them to make organic fertilisers / soil improvers;

• Using them in composting or anaerobic digestion;

• Using the Fish Silage Processing Method (ensiling followed by heat treatment) - same as Category 2 method;

• Using them as a fuel for combustion.

by Zasha Whiteway-Wilkinson, Production Editor, International Aquafeed

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