DEPARTMENT OF BIOLOGICAL SCIENCES,

BAYERO UNIVERSITY KANO, P. M. B. 3011, KANO.

Fishes are important in the development of Nigeria both economically as a source of subsistence income and health - wise as a source of proteins with low cholestrol level in the diets of the populace (Aken’ova, 2000). Endoparasites of some fresh water fishes in Nigeria include the tremotodes Diplostomum spp. Euchinostomum of Clarias garienpinus (Obiekezie) et al, 1982; Onwuliri and Mgbemana, 1987; and Oniye and Adakole, 1999). The cestodes, polyonchbothrium spp were found in the stomach, intestine and rectum of C. lazera from a pond in Ile-Ife (Aderounmu and Adeniyi, 1972; shotter, 1980 and Awa et al, 1984). The nematodes procamallanus laevionchus having the highest percentage of occurrence in all species of fish examined (Ndifon and Jimeta, 1990; Auta et al 1999 and Oniye, 1999). The acanthocephalans Neoechinorrhynchus rutill was found in the intestine of C. lazera (Onwuliri and Mgbemena, 1987).

Documented information on endoparasites of Clarias spp in Kano State are scanty. Except for some works done in Tiga dam by Jimeta (1982) and Ndifon et al (1990), most recent works were carried out in other neighboring states including those by Anosike et al (1992) in Jos, Plateau State; Oniye (1993), Auta el at (1999), Aken’ova (2000) in Zaria and Emere (2000) in Kaduna.

This study was conducted to provide information on the endo-parasites of a Clarias specie because of their importance in the artisanal fisheries of Kano and other Inland States of Nigeria. Such studies could provide valuable information on the culture and management of Clarias sp. in the inland waters of Kano and other parts of Nigeria.

Such studies could provide valuable information on the culture and management of Clarias sp in the inland waters of Kano and other parts of Nigeria.

Wase Dam lies between longitude 8⁰37¹-8⁰45¹E and 12⁰03¹ and 12⁰10¹N in Minjibir Local Government Area approximately 15 kilometers northeast from Kano, the Kano State Capital (Fig 1). It was created by impounding River Jakara which runs together with all the city’s wastes including both domestic and industrial wastes. It’s waters are also used for irrigation and fish production.

The elevation of the region is about 400-750m above sea level. The vegetation of the area is Sudano-Sahelian characterized by the trees with broad canopies not teller than 20m. The climate of the region has a distinct wet and dry season. Normally, mean annual rainfall is about 600mm although there is recurrent variations annually (WRECA, 1990).

Fish sample of Clarias garienpinus were bought from local fishermen at the lake site as soon as they landed and transported to the laboratory in cool boxes containing ice block. The fish were identified using the key produced by Reed (1967).

They were measured for total and standard lengths and weights to the nearest mm and gm respectively. Their genitallia were macroscopically examined for the purpose of separating them into males and females.

The fish were dissected and careful examination of the opened abdominal cavity with it’s organs in-situ was made using hand lens. The gastrointestinal tract (G.I.T.) was removed using forceps unto a petri-dish containing 0.75% saline solution. This was separated into different portions (Oesphagus, Stomach, Gallbladder, intestine and rectum) and placed in different petri-dishes containing saline and slit longitudinally to expose parasites under the dissecting microscope. The body cavity was examined with a hand lens after removing it’s organs.

The number, stage of development, and sex of the parasites for every G.I.T. region were recorded. The fullness of the stomach in each case was noted. Mature parasites were allowed to relax in saline and viewed alive (where possible) under the Binocular microscope. Some were fixed and preserved in 70% alcohol.

Parasites recovered were identified and classified based on external morphology and using the keys provided by Markevich (1963); Roberts (1978); Paperna (1980) and Paperna (1996).

700 specimens of C. grienpinus, ranging in weight from 5-300gm (modal weight, 110g) and total length, 110-350m (modal length, 228mm) were examines for helminth parasites of the alimentary canal. Of this number, 281 (40.14%) were found to be infected by helminth parasites.

A study of the results revealed a total of 3 classes of parasitic helminthes numbering 1041 these classes are the nematodes (40.82%), Cestodes (20.94%) and trematodes (19.02%) as shown in Table 1.

Table 1: Distribution of heiminth parasites in the GIT of C. garienpinus from Wase Dam, Kano.

Trematode Cestode Nematodes

20.94% 40.82%

Key: Pro - Procamallanus Sp.

Po - Polyonchobothrium Sp. Para - Paracamallanus Sp.

Mo - Monobothroides Sp. L.V. - Larval nematodes.

Data concerning attachment sites of the parasite is presented in Table 1 shows that there is great affinity (preference) for the intestine by all the helminthes found (26.80%) followed by the stomach (12.10%). Only 1 cestode was recovered from the gallbladder (7.01%).

Infection varied among the sexes. Females were infected more than males 45.76% and 35.71% respectively. Juveniles were the least infected (24.17%) The infection was found to be higher in females than in males (P>0.01). There was a high correlation between weight and length of the fish (r = +0.98; P>0.05) (Table 2).

Table 2: Relationship between Infection and Weight of C. garienpinus

Because the value of r is more towards 1 at p<0.050 then there is high or strong positive correlation between weight and length & infection of the fish.

There was also a high correlation between level of infection and weight of fish (r = +0.80) and length of fish ( r = +0.84) (P>0.05, Table 3).

The bulk of the diet seen in the stomach of the fish examined was made up of mainly insect larvae and plant material although in some cases seeds, small fishes and some shells of mollusks were also seen. The stomachs of 254 (36.28%) fish were found to be empty.

The result of this investigation revealed the occurrence of 3 helminths parasitizing C. garienpinus in the dam. These are the nematodes, Procamallanus sp. and Paracamallanus sp., cestodes, Polyonchobothrium sp. and monobothroides sp. and metacercarial trematodes. The high infection rate recorded in this investigation indicate that helminth are a major group of parasites involved in fish parasitism in Kano and Nigeria in general. Earlier workers; Ukoli (1987); Ndifon and Jimeta (1990; Auta et al (2000) had subscribed to this observation.

The commonest infection of the fish was caused by a nematode. According to Bakare and Imevbore (1970), Claris sp. are bottom dwellers/feeders, they feed on what is most available and close to them such as detritus, water invertebrates like arthropods, molluscs and mud. Among these invertebrates, there may be intermediate hosts of various parasites which may develop into adults in the gut of fish after consumption especially if it is by a proper definite host (birds, such as gray heron). Judging by the number and type of nematodes parasite found in the fish, it seems that the intermediate host [Mesocyclops (a copepod)] in case of Procamallanus sp. are common in the environment. Royce (1972) concluded that the presence of nematodes in fish lead to decline in population in their natural environment although, this study did not investigate this assertion.

The distribution of helminth parasites in the gut of C. garienpinus showed that the majority of the parasites occurred in the intestine. Similar findings were reported by Khalil (1969); Ugwuzor (1987); Ndifon et al (1990); Oniye (1999); Auta et al (2000) and Emere (2000). This could be due to the conducive nutritional advantage presented by the host’s intestine to the parasites. Onwuliri et al (1989) observed that helminthes sometimes differ in their nutritional and respiratory requirements. In this study, Cestodes were mostly found in the gallbladder and bile duct. This observation is similar to the observation of Paperna (1980).

The sex ratio found in this study indicated that more females than males occurred in the samples fish population Similarly a higher number of helminth parasites were found in females than the males. Statistical test also indicated that there was a significant difference in the prevalence of infection between the females and the males. According to Emere (2000) and Onwuliri and Mbgemena (1987) differences in infection between the two sexes could be due to differential feeding either by quantity or quality of food eaten and as a result of different degrees of resistance to infection. This observation could also be due to the fact that there were simply more females available for infestation. However, the works of Bibby (1972), Hines and Kennedy (1974) and Rumpus (1975) had also shown a rise in the incidence of infection in females, especially gravid ones which may be due to alterations in the general physiological condition of the female host. Infections in the juveniles fish was low compared to the adults. This suggest that food/diet is probably responsible for the burden in parasite species as reported by Dogiel et al (1958); Oniye (2000) and Emere (2000).

The high infection observed in bigger fish in this study may be due to the fact that larger fish provides greater surface for infection than smaller fish as reported by Bishop and Margolis (1955). Roberts (1978) showed that the number of parasites increases with the fish length and suggested that the increase in parasitization could be to parasitic larvae accumulating from year to year as the fish grows older.

A high incidence of infection by metacercarial cysts of trematodes was noted embedded within the body cavity (Table 1) on viscera and amongst fatty tissue covering the viscera. These are probably Strigeidea (Clinostomum, Neascus) cysts as reported by Markevich (1951) and Paperna (1996).

The encapsulated larval nematodes found parasitise only the body cavity and visceral organs. Worms were found coiled within these encapsulations. A similar observations was made by Paperna (1980; 1996).

The present investigation shows evidence of parasitic helminth infections of C. garienpinus in Kano State. The presence of these parasites might elicit some pathological effects on the fishes by retarding their growth, causing tissue disruption and even death.

It is thus apparent that significant parasites infestation of C. garienpinus in Wase Dam has been established. The extent of the adverse impacts of such parastic loads on fish productivity in the lake was, however, not established. However, it might be assumed that parastic infection of fish does reduce their productivity, as shown by several studies (Onwuliri et al 1989 and Anosike et al 1992). Further studies in the parasites of C. garienpinus and their impact on their productivity in Wase Dam might be necessary to allow for a more rational management of the fisheries of the dam.