Fish and shellfish diseases

Wageningen Bioveterinary Research (WBVR) has a specialised fish and shellfish diseases laboratory. The laboratory was set up in 1985 and offers broad experience on diseases of cultured fish for human consumption, ornamental and wild fish, crustaceans and shellfish.

Healthy aquaculture

Fish production via aquaculture is increasing strongly worldwide. One of the threats to intensive aquaculture is the occurrence of contagious fish, crustaceans and shellfish diseases, which can cause serious illness and death and thereby economic losses.

Role of Wageningen Bioveterinary Research

At the specialised laboratory in Lelystad, accredited and fast diagnostics are performed to identify new outbreaks at an early stage. We offer broad experience and expertise on various fish and shellfish diseases. We are consulted frequently for our diagnostic service, expertise on diseases, and as partner for collaboration in research and network projects by both national and international parties.

Tasks

Diagnosing diseases for the aquatic industry, and the ornamental and wild fish branches:
- In case of fish disease at fish farms
- At suspicion of notifiable fish and shellfish diseases, in cooperation with the Food and Consumer Product Safety Authority (NVWA)
- For certification of live fish for export, in cooperation with the NVWA
Serving as a knowledge and advisory centre for the Dutch Ministry of Agriculture, Nature and Food Quality (LNV) and provide consultancy to the aquaculture branch regarding fish and shellfish diseases
Research on fish and shellfish diseases that occur in the Netherland, with specialisation in eel and carp diseases

National Reference Lab

The laboratory is the Dutch National Reference Lab (NRL) for fish and shellfish diseases for the EU. It was the first fish diseases laboratory in Europe accredited for quality standards ISO 9001 and 17025 (EN 45001). The laboratory has an impressive national and international network, in which knowledge and materials are exchanged.

Appointment and order form

Live diseased or healthy fish and shellfish can be diagnosed at appointment (after a phone call) with the Fish and Shellfish Disease Laboratory in Lelystad, preferably via a veterinarian. When submitting research material, please fill in the submission form for fish diseases, print it and send it along.

For diagnostic research - necropsy (including parasitology), bacteriology, virology, and histopathology - reasonable rates are charged.

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Export certification

Export certification is arranged via the Dutch Food and Consumer Product Safety Authority (NVWA). A notification period of 14 days prior to this must be taken into account.

Procedure

Following the anamnesis, necropsy is performed, including external and internal investigation for parasites. At suspicion of a virological or bacteriological disorder, further tests are performed. For example, in the event of a bacteriological suspicion, specimens from the lesions and internal organs of the fish are inoculated onto agar. For virology organs of the fish are sampled, and in histopathology (microscopy of sections of affected tissue) pieces of tissue are put into a fixative.

Once the diagnostic tests have been completed, a diagnosis is made. This is indicated in the written results.

Bacteriology

The inoculated agar plates are incubated at room temperature, as fish are cold-blooded animals and their pathogenic organisms have adapted to that temperature. In case a pure culture of bacteria results, an antibiogram is made, so that the fish owner can choose an appropriate antibiotic to treat the disease. In parallel to this process, the bacteria are characterized by classic and/or molecular techniques.

Virology

WBVR has many PCR tests for the virus diagnostics of fish, crustaceans and shellfish.

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Histopathology

For histopathology, the fixed tissue is sliced and stained in such a way that it can be examined with a microscope. This makes it possible to see alterations at cell level that indicate a viral, bacteriological or other disease. This method also enables detection of very small parasites in the tissue or in cells.

Diagnosis of shellfish diseases

For research on live shellfish, they are fixed and processed for histopathology. Light microscopy is used to read the sections. At the same time, inoculations can be used for bacteriological research. WBVR also offers PCR tests for the most important shellfish pathogens.

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Research examples of WBVR

The laboratory has studied various fish disease subjects in more detail, with or without infection trials: the swimbladder parasite (Anguillicola crassus) in eels, common eel parasites in the open waters, eel bacteria and currently eel viruses. In addition, various molecular detection methods have been developed for KHV (koi herpes virus), HVA (eel herpes virus), Bonamia (oyster parasite) and Nocardia (shellfish bacteria). Scientific publications have appeared based on the results of these studies. The scientists collaborate with other partners in new research projects that optimally utilize the specific knowledge of all participants.

Advice

As a member of (inter-)national advisory committees, the laboratory experts also give advice to parties like the Ministry of LNV, the EU, the EFSA (European Food Safety Authority), the OIE and FAO. The laboratory also publishes frequently in professional bulletins of the aquaculture and ornamental fish industry, and in international peer reviewed fish and shellfish disease journals, and books. Researchers of the laboratory present posters and oral presentations at (inter-)national meetings and conferences.