Parasitic Diseases in cultured fishes

Dr. Mohamed S. Mohamed MarzoukProfessor of Fish Diseases and Management , Faculty of

Veterinary Medicine, Cairo University

By

Parasitic Diseases of cultured fishes

Common Parasites in cultured fishes:

Fish Protozoa (unicellular).

Fish Helminthes (multi-cellular).

Fish Parasitic Crustaceans.

Commom protozoa in cultured Fishes:

1. Exteranl cilliated protozoa:

Ichthyophthirius multifillis

Chilodonella spp.

Trichodina spp.

2 .Internal fish protozoa:

Flagellated Hexamita spp.

Ichthyophthirium multifilis trophozoit (Stained )

Ichthyophonus multifillis (unstained)

Stained Trichodina from skin mucus scraping

Pathogenesis of external protozoa

Protozoal invasion

Skin cellular irritation 1. Abnormal swimming

2 .Excessive mucus

Skin cellular destruction

1. Haemorrhages

2. Erosions and ulcers

3. C.T capsules (White spots).

Life cycle of Ichthyophthiriosis

Clinical signs

Abnormal swimming ( Flashing, circling, sluggish and itching ).

Surfacing and gasping ( Asphyxia ).

Excessive skin mucus ( patchy then generalized ).

Pathognomonic white spots (Ichthyophthiriosis).

Emaciation and death.

Skin haemorrhages, erosions and ulcerations.

White spot disease

Cryptocarion irritans infection in marine fish

Diagnosis of External parasitic Diseases

1. History ( new introduced fish, water parameters,………

2. Clinical signs and lesions.

3. Demonstration and identification of the causative parasites

Skin and gill mucus scraping (wet mount). Stained skin and gill mucus smears.

Treatment of External parasitic Fish Diseases

External chemical treatment

Dip treatment Bath treatment Flush treatment Indefinite bath treatment

Non-chemical treatment

Increase water temperature in White Spot disease Use of ultraviolet radiation in re-circulating system

Types of Chemical treatments

1 .Disinfectants:

Pot. Permenganate. Malachite green. Formaline. Na Cl. Acriflavin. Methylene blue.

2. Pesticides:

Chlorinated Hydrocarbones.Organophosphates.

Control of Fish diseases in infected fish farms

In infected earthen ponds:

o Drainageo Drynesso Disinfection using quick lime

In infected concrete or fiberglass fish tanks:o Drainageo Disinfection with strong antiseptics

Hexamitiosis Systemic infection caused by an internal flagellated

protozoa

Causative protozoa:

Hexamita intestinalis

Mode of infection and transmission:

1. Infection through ingestion.2. Transmission is from dead fish and contaminated water body.

Pathogenesis

Hexamita is normal inhabitant of intestine

Small numbers Large numbers

Intestinal irritation

Intestinal destructionNo signs

Excess mucus

Systemic form

Off food & emaciation

Hole in head

Clinical signs:

1. Off food.

2. Emaciation and tucked up abdomen.

3. Mucus shreds from the vent.4. High mortality in severe cases.5. Hole in the head in systemic form (Fistula behind the head exuding white material).

Diagnosis

Clinical signs and lesions (Non-confirmative)

Laboratory ( Confirmative)

Sampling ( Intestinal mucus )

QualitativeQuantitative (Count/ MF)

0 - 5 = Negative5 – 15 = Mild15 -30 = Moderate30 – 100 = SevereMore than 100 = Marked

Treatment and control

1. Expulsion

2. Hexamiticides

Saline purgative (MgSO4)

1. Aresenical (Carbersone).

2. Murcurial (Calomel).

Not to be used in food fishes

Sulfonamides

Can be used in food fishes

Fish Helminthosis

Helminthes of fishes

Platy helminthes

Round worms

Trematodes

Cestodes Larvae A dults

Fish Trematodes

1. Monogenea 2. Digeanea

Gill flukes Skin flukesAdults

Encysted metacercaria

Gill

flukes

1. Dactylogyridae

2. Cichlidogyridae

Dactylogyrus vastator (D. vastator)

Cichilidogyrus tilapiae (C. tilapiae)

D. vastator

C. tilapiae

Gill fluke attached to fish gill filaments

G. elegans

Skin fluke attached to fish skin

Haemorrhagic granuloma of Lernea copepode

Lernea cyprinicae

Anchor2 egg sacs

Fish lice ( Argulus sp.) attached to fish skin

Ventral view of Fish Lice