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Abstract
Summary
Parasitic diseases is considered one of the most important causes of
physiological and metabolic changes in fish .So the study of parasitic
infection in different fish is considered important step in the field for
controlling the spreading of parasites and producing fish of high quality
protein.
The present study carried out for detection of different parasites in
African sharptooth catfish (Clarias gariepinus) in Assiut Governorate, in
these study collected (240) fish (20/month) from C. gariepinus of different
sexes and weights from The River Nile of Assiut Governorate within one
year during different seasons. The period of study which extended from the
beginning of May, 2009 till the end of April, 2010.The fish was subjected
to clinical and parasitological examination.
The main clinical signs showed in infected fish with protozoal
infection were:
The gills appeared pale colour, covered with excessive mucous. In
some fish gills were congested and swollen, while in others were
necrosed or hyperplasia of gills lamellae also observed. On others fish
creamy white cyst-like nodules, ovoid or round in shape were showed in
both gills or Extra-respiratory organ, opening of these cysts gave white
creamy viscous pus like fluid containing a great number of spore. In case
of infected fish with internal protozoa (Trypanosoma sp., Hexamita sp.)
appeared emaciation, pale gills, abdominal distention, intestinal contents
were yellow, watery and contain excess mucus, haemorrhage in the
intestine with red vent. In some examined fishes were showed sunken
abdomen, swelling in spleen and kidney with exophthalmia, yellow
discolouration of musculature and skin might detected.
In helminthes infection gills were appeared pale, swollen ,
completely or partially covered with slime , the naturally infested fish
characterized by paler or dark colour of skin than normal , erosion and
ulceration in different parts of the body surface were also shown . While
in case of intestinal helminthes the infested intestine were congested and
had watery yellowish mucous.
Parasitological examination of examined fish revealed that the total
infection rate was 95%, prevalence rates of infection with protozoal,
Cnidaria, Dinoflagellate, helminthes and encysted metacercariae were
38.8, 16.7, 69.6, 72.1 and 56.3% respectively. Mixed infection with more
than one parasite was observed in 86.3%, while single infection was
detected in 8.8% .
Gills were showed the highest infection rate with different
parasites which reach the percentage to 85%, followed by Intestine
(62.5%) then Muscle (55%) ,Liver (26.3%), Extra-respiratory organs
(15%) ,Blood(12.9%) and the lowest infection rate was detected in
Kidney (9.2%).
*Four species of protozoal parasites were identified in the present work:
1-Trichodina species. 3- Trypanosoma species.
2- Chilodonella species. 4- Hexamita species.
1- Trichodina species
The prevalence rate of infestation with Trichodina species in
examined fish reached to 26.7% .The highest prevalence rate detected in
young fish (100-300gm) which reached to 30.8%. The maximum
prevalence rate observed in Winter season with prevalence rate 38.3%
.The study detected the highest infestation rate occurred in male fish with
prevalence 29.9%.
2- Chilodonella species
The infestation rate of Chilodonella species in examined fish
reached to 5.8% .The highest prevalence rate occurred in young fish
(100-300gm) which reached to 9.2%. Autumn had maximum prevalence
rate (11.7%).The female fish harbouring the maximum infestation rate
(6.2%).
3- Trypanosoma species
The infestation rate of Trypanosoma species in examined fish
reached to 12.9% .The highest prevalence rate occurred in young fish
(100-300gm) which reached to 20%. Spring harbouring maximum
prevalence rate (21.7%).The female fish harbouring the maximum
infestation rate (14.2%).
4- Hexamita species
The infestation rate of Hexamita species in examined fish reached
to 2.5% .The highest prevalence rate occurred in young fish (100-300gm)
which reached to 4.2%. Autumn &Spring had maximum prevalence rate
(5%).The male fish harbouring the maximum infestation rate (3.1%).
*One species of Cnidaria parasites were identified in the present work:
-Henneguya species
The prevalence rate of infestation with Henneguya species in
examined fish reached to 16.7% .The highest prevalence rate detected in
medium weight fish (301-400gm) with percentage 19.6% . Henneguya
species reached to the maximum infestation rate in Spring &Winter
season with rate 21.7% .The study detected the highest infestation rate
occurred in male fish with prevalence 18.9%.
*One species of Dinoflagellate parasites were identified in the present
work:
-Piscinoodinium species
piscinoodinium species appeared in these study with prevalence
69.6% .The highest prevalence rate observed in both weight medium and
large one (301-400 gm and 401-600 gm) which reached in 72.5% in both
weight. The highest prevalence rate detected in Winter season (88.3%).
The male of examined fish harbouring the maximum infestation rate
(70.1%).
Observed in the present work the infection rate of Nematodes was
21.7% .The highest infection rate detected in large weight of examined
fish (401-600 gm) with prevalence 29.1% .Summer season harbouring the
maximum infestation rate with prevalence 25%.The female of examined
fish harbouring the maximum infestation rate with prevalence rate 25.7%.
Identified sample of nematodes as Procamallanus laeviconchus .
The prevalence rate of Cestodes was 41.7%. Large weight of
examined fish (401-600 gm) had highest infection with prevalence
50.7%. Spring season harbouring the maximum infestation rate with
prevalence 53.3%. The maximum infestation rate appeared in female of
examined fish with rate 43.4%. Identified sample of Cestodes as
Polyonchobothrium clarias.
In these work the infection rate of Trematodes was 59.2%, the
infection rate of Monogenea in examined fish was 35%. Two species of
Monogenea were detected in the present work:
a- Quadriacanthus sp. b-Gyrodactylus sp.
The prevalence rate of infestation with Quadriacanthus species
was 28.8% .The highest prevalence appeared in young fish (100-300gm)
with prevalence 44.2%. The maximum infection rate detected in Spring
season with prevalence 48.3% .The male of examined fish harbouring the
maximum infestation rate with prevalence rate 33.1%.
Gyrodactylus species detected in these study with prevalence
6.3%.The highest prevalence rate of infestation were observed in large
one (401-600 gm) with percentage 7.2%. The maximum infection rate
appeared in Spring season with prevalence 10%.The male of examined
fish harbouring the maximum infestation rate with prevalence rate 7.1%.
In total examined fish the infestation rate with adult digenea was
24.2%.
The highest infestation rate with adult digenea appeared in young
fish (100-300 gm) 35.3%. Summer had maximum infestation rate which
reached to 55%. Female harbouring the high prevalence with rate 24.8%.
Seven species of trematodes were detected in the present work:
1-Haplorchis spp 4- Acanthostomum spiniceps
2-Orintocreadium batrachoides 5- Glossidium aswanensis
3-Astiotrema lazeri 6-Allocaredium aswanensis
7-Allocaredium bynni
The total prevalence of Encysted metacercariae in examined fish
was 56.3%. The high prevalence observed in young fish (100-300 gm)
with prevalence 59.2%. The maximum infestation rate appeared in
Summer (78.3%).Male had high prevalence rate (57.5%).
Two forms of E.M.C. were detected in the present work:
a- Macroscopic E. M. C b-Microscopic E.M.C
Macroscopic E. M. C. detected in muscular tissue only and their
prevalence was 2.5% .While Microscopic E. M. C. detected in muscular
tissue , Liver, Kidney and gills of examined fish, the prevalence was 55%
,26.2% , 9.2% and 7.5% ,respectively.