Sea lice

NeemCo is developing, in collaboration with a variety of institutions, a control of ectoparasites of farmed fish. The work initially is focused on the sea louse (Lepophtheirus salmonis) which is the scourge of farmed salmon in Scotland and other countries where the fish are farmed. Riddance™ is administered by inclusion in the diet.

Several trials conducted under Good Experimental Practice have shown the following:

  • Use as a food supplement reduces the burden of immature lice by more than 70%
  • Egg production by females is completely eliminated
  • There is no accumulation of the a.i. in the fish muscle fillet, eliminating pre-market withdrawal interval
  • When the dose of a.i. is adequate for the elimination of the parasite, fish show no reluctance to consume the diet

The results so far suggest that other ectoparasites, particularly crustaceans, and others with complex development patterns, will be susceptible to control by neem.

Patents have been applied for in all the major salmon farming countries, and one has been granted by Denmark to cover the Faroe Islands.

Riddance™ should benefit:

  • Commercial salmon farmers: ectoparasite control, costs, losses, expansion issues, and PR.
  • Wild salmon fishing interests indirectly by reducing overall sea louse numbers – a significant political issue.
  • Regulators by offering a product to reduce the use of current costly and controversial sea lice controls.
  • Governments through resolving competing interests: salmon farmers, fishing, and environmental concerns.


The active is already approved for food use as a plant protection product (PPP) (i.e. mammalian toxicity work complete) in key countries including the EU, USA, Australia, Japan, New Zealand, and Chile. This shows its efficacy, safety to mammals, and low environmental impact in terms of production, use, and effect on soil, water, domestic and farm animals, non-target species, and fish.


Resistance to Riddance

Resistance is a significant issue with neurotoxin based pesticides, such as organophosphates, pyretheroids, and avermectins.
Neem extracts used as commercial biocides and plant protection products for almost 20 years in the USA and EU, and as yet, there have been no reports of signs of resistance in target organisms.


Sea lice larves

Current research project

Toxicity of RiddanceTM and its cataboilic products to various marine and fresh-water organisms

Several studies are being pursued to determine the effect of the active ingredient and its breakdown products against a number of organisms.

They include:

  • the brine shrimp (Artemia salina)
  • Hydra spp.
  • the edible mussel (Mytilus edulis)

These studies are part of our long –term project concerned with registration of RiddanceTM as a treatment for ectoparasites in farmed fish.



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