“Why is it so dangerous to be a cleaner fish? (7326)”

Why is it so dangerous to be a cleaner fish?

Cleaner fish are lumpfish and various wrasse species that are used as a part of the strategy to control salmon lice (Lepeophtheirus salmonis) in aquaculture. Every year, millions of cleaner fish are introduced into net pens to work as delousers. However, the role as lice-eater is considered one of the most hazardous “jobs”. Why is being a cleaner fish so risky? This presentation will explore the findings of the Norwegian Fish Health Report regarding the health and welfare of cleaner fish and examine whether conditions have improved in recent years.

Methodology:

The last decade the annual Norwegian Fish Health report have described the health and welfare situation for cleaner fish. The data used in the report comes from biomass statistics provided by the Directorate of Fisheries. In addition, a survey is distributed to fish health personnel and inspectors from the Norwegian Food Safety Authority to gather further insights.

Results:

Although the use of cleaner fish has declined over the past five years, more than 24 million were still used in 2024. This reduction reflects the growing concern among fish health professionals, who report that cleaner fish are being used less frequently or are being phased out altogether due to significant health and welfare challenges. There are also uncertainties regarding their ability and effectiveness to eat lice (delousing effect), and exact mortality rates are poorly documented.

The natural habitat for the different cleaner fish species differs significantly from the conditions in the net pens that are adapted for salmonids. It’s therefore not surprising that cleaner fish struggle to adapt when tolerance limits for factors such as handling, temperature, weather, and current strength differ from salmonids.

According to the Norwegian Animal Welfare Act, animals are not only to be protected but should be ensured a good quality of life and be treated with respect. Cleaner fish are entitled to the same protection as farmed salmonids. Yet in practice, cleaner fish as tools in delousing efforts, is exposed to ie. emaciation, injuries due to handling, impact from different diseases and environmental conditions, that cause mortalities and poor welfare.

1. HARASIMCZUK, EWA, NORWEGIAN VETERINARY INSTITUTE, Presenter
2. Gismervik, Kristine, NORWEGIAN VETERINARY INSTITUTE, Author