Fish Louse
Introduction
The fish louse is a metazoan parasite of freshwater fish.
The louse has a sharp stylet along the ventral midline that it uses to pierce the skin of the fish. It then injects digestive enzymes into the surrounding tissues and then feeds on the digested bodily fluids.
A consequence of this is localised inflammation and irritation of the skin, which is a welfare concern. It also allows secondary opportunistic infections to develop, and can transit bacterial and viral infections directly.
Diagnosis
The louse can be seen with the naked eye, growing up to 7 mm in length.
Treatment
Infestations can be treated with an increase in water salinity. If this is ineffective organophosphates or chitin inhibitors can be used.
| Fish Louse Learning Resources | |
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 Test your knowledge using flashcard type questions |
Ornamental Fish Q&A 10 |
References
Frye, FL & Williams, DL (1995) Self-Assessment Colour Review - Reptiles & Amphibians Manson
Maclean, B (2006) Common dermatoses of ornamental fish and amphibians In Practice 2006 28: 604-613
Southgate, P (1994) Laboratory diagnosis of fish disease In Practice 1994;16:252-255
Stuart, N (1988) Common skin diseases of farmed and pet fish In Practice 1988 10: 47-53
Wildgoose, W (1998) Skin disease in ornammental fish: identifying common problems In Practice 1998 20: 226-243