Difference between revisions of "Fish Louse"

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(Created page with "==Introduction== 250px|thumb|right|'''Fish Louse (''Argulus sp.'') attached to the skin of a fish ''' The '''fish louse''' is a '''metazoan parasite''' of '...")
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==Introduction==
 
==Introduction==
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[[File:Argulus.jpg|250px|thumb|right|'''Fish Louse (''Argulus sp.'') attached to the skin of a fish (Wikimedia Commons)''']]
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[[File:Argulus.jpg|250px|thumb|right|'''Fish Louse (''Argulus sp.'') attached to the skin of a fish ''']]
  
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The '''fish louse (''Argulus spp.'')''' is a '''metazoan [[Crustacea|crustacean]] skin parasites''' of '''freshwater fish'''. They pose a major threat to the health of commercially produced fish.
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The '''fish louse''' is a '''metazoan parasite''' of '''freshwater fish'''.  
  
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==Life Cycle==
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The louse has a sharp stylet along the ventral midline that it uses to pierce the skin of the fish. It then injects digestive
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The parasite's life cycle is '''direct'''. The lice mate on the fish and the female then lays her eggs on surfaces or plants within the habitat. These then progress through a series of '''metamorphic stages''', each of which moults its exoskeleton in order to grow.
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enzymes into the surrounding tissues and then feeds on the digested bodily fluids.  
  
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After '''4 days''' the hatched adult crustacean will seek out a host fish to feed on.
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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.
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The total life cycle takes '''30-100 days''' and is '''temperature dependent'''. Eggs can undergo '''latency''' and delayed hatching if water temperatures are not suitable over Winter.
 
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==Pathology and Clinical Signs==
 
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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 feeds on the digested bodily fluids by sucking them out with its '''proboscis'''.
 
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The damage caused by the fish louse is two-fold; firstly '''localised inflammation and irritation''' of the skin caused directly by the parasite and secondarily the risk of developing '''opportunistic infections''', both '''bacterial and viral''' via the damaged skin. [[Pseudomonas species - Overview|''Pseudomonas spp.'']] and [[Aeromonas species - Overview|''Aeromonas spp.'']] are often of particular concern, as they can potentially invade the [[Gills|gills]].
 
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Fish may show '''rubbing and flashing behaviour''' due to the intense irritation caused by the infection.
 
  
 
==Diagnosis==
 
==Diagnosis==
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The louse can be seen with the '''naked eye''', growing up to '''7-10 mm''' in length. They appear as '''flat, oval, darkly coloured spots''' on the skin of the fish and are easier to see on fins or when moving. Red lesions may be visible from previous feeding areas.
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The louse can be seen with the '''naked eye''', growing up to '''7 mm''' in length.  
  
 
==Treatment==
 
==Treatment==
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It is vital that any treatment plan is effective against both '''adults and juvenile stages''' of the parasite.
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Infestations can be treated with an '''increase in water salinity'''. If this is ineffective '''organophosphates''' or '''chitin inhibitors''' can be used.
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Infestations can be treated with an '''increase in water salinity'''. If this is ineffective, [[Ectoparasiticides|ectoparasiticides]] such as '''organophosphates''' or [[Ectoparasiticides#Modes of Action|'''chitin inhibitors''']] can be used. Three treatments of organophosphates are usually required to eliminate all life stages. It should be noted that organophosphate treatment is not permitted in fish in the UK and should be confirmed in any other region before use.  
 
  
 
{{Learning
 
{{Learning
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==References==
 
==References==
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Fishdoc (2009) '''Argulus/Fish Louse''' at http://www.fishdoc.co.uk/disease/argulus.htm, accessed online 22/11/2011
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Frye, FL & Williams, DL (1995) '''Self-Assessment Colour Review - Reptiles & Amphibians''' ''Manson''
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Lewbart, G. A. (1998) '''Self-Assessment Colour Review of Ornamental Fish''' ''Manson''
 
  
 
Maclean, B (2006) '''Common dermatoses of ornamental fish and amphibians''' ''In Practice 2006 28: 604-613''
 
Maclean, B (2006) '''Common dermatoses of ornamental fish and amphibians''' ''In Practice 2006 28: 604-613''
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Stuart, N (1988) '''Common skin diseases of farmed and pet fish''' ''In Practice 1988 10: 47-53''
 
Stuart, N (1988) '''Common skin diseases of farmed and pet fish''' ''In Practice 1988 10: 47-53''
  
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Wildgoose, W (1998) '''Skin disease in ornamental fish: identifying common problems''' ''In Practice 1998 20: 226-243''
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Wildgoose, W (1998) '''Skin disease in ornammental fish: identifying common problems''' ''In Practice 1998 20: 226-243''
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{{review}}
 
  
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{{OpenPages}}
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[[Category: To Do - Siobhan Brade]]
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[[Category:Crustacea]]
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[[Category:To Do - Manson review]]
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[[Category:Fish Diseases]]
 

Revision as of 14:21, 14 September 2011

Introduction

Fish Louse (Argulus sp.) attached to the skin of a fish

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
FlashcardsFlashcards logo.png
Flashcards
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

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