Culture suitability of two exotic catfishes (Clarias gariepinus and Pangasius hypopthalamus) with an indigenous catfish (Heteropneustes fossilis)

Culture experiment of African catfish ( Clarias gariepinus) and Thai pangas (Pangasius hypopthalamus) with indigenous stinging catfish (Heteropneustes fossilis) was conducted in the laboratory. The study was conducted for two experiments, where C. gariepinus and P. hypopthalamus were used separately with H fossilis for a duration of 2l days with three feeding treatments, viz. Tubificid worms (T1), SABINCO feed (T2), and no supplemental feed (T3). In experiment 1, the initial length and weight of 4.4cm and 0.60g of C. gariepinus became 6.74cm and 2.33g when fed Tubificid worms, 7.07cm and 2.84g when fed SABINCO feed in the treatment without supplemental feed the final length and weight were 3.67cm and 0.3lg at the end of 21 days of trial. The final length and weight of H fossilis reached 4.55cm and 0.53g from the initial 3.3cm and 0.25g under the treatment fed Tubificid worms while those fed SABINCO feed showed a length and weight of 4.37cm and 0.45g respectively. However, both the initial length and weight were reduced to 2.85cm and 0.12g respectively in the treatment without supplemental feed. In experiment 2, the initial length and weight of 4.37cm and 0.57g of P. hypopthalamus became 5.57cm and 0.57g when fed Tubificid worms, 4.85cm and 0.82g when fed SABINCO feed in the treatment without supplemental feed the final length and weight reduced to 3.95cm and 0.34g at the end of 21 days of trial. The final length and weight of H fossilis reached 5.19cm and 0.82g from the initial 3.25cm and 0.20g under treatment fed Tubificid worms while those fed SABINCO feed showed the final length and weight of 4.93cm and 0.70g respectively. And both the initial length and weight were reduced to 3.07cm and 0.04g respectively in the treatment without supplemental feed. No predatory effect of C. gariepinus and P. hypopthalamus on H fossilis was observed in the experiments.

Production of triploid African catfish, Clarias gariepinus (Burchell), using chromosome manipulation techniques

An experiment was conducted to induce triploidy in African catfish, Clarias gariepinus, using heat shock and cold shock techniques. Cold shock at a temperature of 0± 1°C and 5±1°C for a duration of 15, 30, 45 and 60 min and heat shock at a temperature of 40±0.5°C and 41 ±OS C for a duration of 1, 2 and 3 min was given to induce triploidy 5 min after fertilization. Maximum percentage of triploids (91.4%) were obtained in the heat shock at a temperature of 40±0SC for a duration of 1 min whereas cold shock at 0± 1 C for a duration of 60 min yielded 90% of triploids. Chromosome analysis revealed that diploids have 54 chromosomes and triploids have 81 chromosomes. The erythrocyte measurements of the minor axis and major axis were 1.17 times larger in treated fish than in controls. The growth studies showed that the growth rate was not significantly affected in triploids.

Comparison of effectiveness of heat and cold shocks applied in the induction of gynogenesis in Clarias gariepinus (Burchell)

An experiment was conducted to optimize the procedure of gynogenesis in African catfish, Clarias gariepinus by suppressing meiotic and mitotic cell divisions in fertilized eggs. Gynogensis was conducted by fertilizing normal eggs with UV-irradiated sperm followed by either heat or cold shocking Irradiation of spermatozoa was given for a duration of 1 min and the eggs were fertilized in vitro. Cold shock at a temperature of 3± 1°C for a duration of 30 and 60 min and heat shock at a temperature of 39± 1°C for a duration of 1 and 2 min was applied to induce diploidy. Higher percentage of hatching (68.66) was observed for meiotic gynogens at a shock temperature of 39± 1°C for a duration of 1 min, 5 min after fertilization (af). Higher percentage of mitotic gynogenetic induction (15.33) was observed at a temperature shock of 39± 1°C for a duration of 1 min, 30 min af.

Growth performance and nutrient utilization of catfish Clarias gariepinus fed varying inclusion level of fermented unsieved yellow maize

This study was conducted using 150 fish of Clarias gariepinus to investigate the growth performance and nutrient utilization of Clarias gariepinus fed five treatment diets containing varying inclusion level of fermented unsieved maize. The diets were grouped into CT, T1, T2, T3, and T4 with inclusion levels of 25%, 50%, 75%, and 100% of fermented unsieved maize respectively. Highest weight gain was recorded in T4 with value of 10.24 and lowest weight was recorded in CT with 9.17. High FCR were observed in T2 with value of 0.70 and lower value was observed in T4 with value of 0.62. While, T2, T3, and T4 have highest survival rates with values of 90% in each treatment CT and T1 recorded 80% and 70% respectively. There was a significant (p< 0.05) difference between the food conversion ratios treatment T4 with the best value and other treatments. There was a significant (p< 0.05) difference between the levels of fermented unsieved maize inclusion and the specific growth rate of the experimental fish. The highest value of protein level and feed efficiency were observed in T4 at significant difference level (p< 0.05) than other treatments. It was concluded that fermentation of maize in fish feed has positive effects on the nutritional value of the feed. It is recommend that fermented maize can replace raw maize in fish feed diet for growth performance. KEYWORDS: Fermentation, yellow maize, Clarias gariepinus, Fish, Feed.

Growth performance and nutrient utilization of catfish Clarias gariepinus fed varying inclusion level of fermented unsieved yellow maize

This study was conducted using 150 fish of Clarias gariepinus to investigate the growth performance and nutrient utilization of Clarias gariepinus fed five treatment diets containing varying inclusion level of fermented unsieved maize. The diets were grouped into CT, T1, T2, T3, and T4 with inclusion levels of 25%, 50%, 75%, and 100% of fermented unsieved maize respectively. Highest weight gain was recorded in T4 with value of 10.24 and lowest weight was recorded in CT with 9.17. High FCR were observed in T2 with value of 0.70 and lower value was observed in T4 with value of 0.62. While, T2, T3, and T4 have highest survival rates with values of 90% in each treatment CT and T1 recorded 80% and 70% respectively. There was a significant (p< 0.05) difference between the food conversion ratios treatment T4 with the best value and other treatments. There was a significant (p< 0.05) difference between the levels of fermented unsieved maize inclusion and the specific growth rate of the experimental fish. The highest value of protein level and feed efficiency were observed in T4 at significant difference level (p< 0.05) than other treatments. It was concluded that fermentation of maize in fish feed has positive effects on the nutritional value of the feed. It is recommend that fermented maize can replace raw maize in fish feed diet for growth performance.

A survey of pest (Dermestes maculatus) infestation of dried preserved Clarias gariepinus: its effect on nutrient quantity and quality

Studies on the nutrient composition of smoked-dried Clarias gariepinus were carried out, to assess the effects of pest infestation on the dried catfish from two different market (Abakpa and Kpirikpiri market) area in Abakaliki Metropolis, Ebonyi State, Nigeria. Fish samples from the two markets where kept for pest to infest it and it were taken to Biochemistry Laboratory of Food Science and Technology in Ebonyi State University to assess the damage of pest on dried catfish using standard methods. There was a significant different among the mean weight of fish from the two markets (Abakpa and kpirikpiri; 19.13kg and 18.98kg respectively) compared with the mean weight of the control 20.09kg. There was a variation in the proximate composition of the fishes from the two markets compared with the control, the decreases of the proximate composition are: crude protein from 60.07% to 40.27%; fat from 8.35% to 5.90%; moisture content from 11.67% to 10.67; fiber from 12.93 to 11.93; ash from 4.02% to 3.54% and carbohydrate 12.67% to 5.89%. The longer the storage periods of the infested smoked fish the more the tissue was degraded. Proper handling and storage of dried catfish are required to prolong the shelf life and nutrient content of dried catfish.

Heavy metal concentrations in some organs of African catfish (Clarias gariepinus) from Eko-Ende Dam, Ikirun, Nigeria

The contents of the heavy metals Fe, Zn, Cu, Mn, Pb, Cd and As were examined in the liver, heart, gills, kidney and muscles of the fish Clarias gariepinus from Eko-Ende dam in Ikirun, the capital of Ifelodun Local Government of Osun State, Nigeria. C. gariepinus is the fish of choice and the most demanded in the southwest of Nigeria. The highest metal concentrations were in the liver and the gills while the lowest was in the muscles. The general deceasing order of metal accumulation in the organs was Fe > Zn > Cu > Mn > Cd. Lead and arsenic were not detected in any organ. The values were of lower concentrations than found in many other dams and rivers in Nigeria and some other countries. The values were also lower than the FAO/WHO recommended maximum limits in fish samples, making the fish to be safe and not of any hazards for the consumers.

Studies on induced breeding of Clarias gariepinus (Burchell, 1822) in hapa pens

Induced breeding of Clarias gariepinus was conducted monthly in hapa pens, set up in Otamiri river for nineteen months (June 1993 - December 1994). Results of natural fertilization were unsatisfactory as few eggs were fertilized. Mean relative fecundity, percentage fertilization, percentage hatching and percentage fry survival were: 15.86 ± 1.95 x 10', 18.92 ± 5.28%, 13.50 ± 3.8% and 6.42 ± 0.72%. Results from artificial fertilization were as follows: Mean relative fecundity, 13.80 ± 2.85 x 10', percentage fertilization, 81.91 ± 2.28%, percentage hatching, 86.10 ± 2.46% and percentage fry survival, 21.40 ± 1.89% respectively. The success of artificial fertilization depended largely on the latency period of 9-11 hours and this suggests that induced breeding in pens is feasible. The poor results from natural fertilization were attributed to lack of adequate substrate for the male fish to display courtship and subsequent fertilization of eggs.

Neuromusculature of Gyrodactylus rysavyi, a monogenean gill and skin parasite of the catfish Clarias gariepinus

Phalloidin fluorescence technique, enzyme cytochemistry and immunocytochemistry in conjunction with confocal scanning laser microscopy were used for the first time to describe the nervous and muscle systems of the viviparous monogenean parasite, Gyrodactylus rysavyi inhabiting the gills and skin of the Nile catfish Clarias gariepinus. The body wall muscles are composed of an outer layer of circular fibres, an intermediate layer of paired longitudinal fibres and an inner layer of well-spaced bands of diagonal fibres arranged in two crossed directions. The musculature of the pharynx, intestine, reproductive tract and the most prominent muscles of the haptor were also described. Two characteristic muscular pads were found lying in the anterior region of the haptor in close contact with the hamuli. To each one of these pads, a group of ventral extrinsic muscles was connected. The role of this ventral extrinsic muscle in the body movement was discussed. The mechanism operating the marginal hooklets was also discussed. The central nervous system (CNS) consists of paired cerebral ganglia from which three pairs of longitudinal ventral, lateral and dorsal nerve cords arise. The nerve cords are connected at intervals by many transverse connectives. The CNS is better developed ventrally than dorsally or laterally and it has the highest reactivity for all neuroactive substances examined. Both the central and the peripheral nervous system (PNS) are bilaterally symmetrical. Structural and functional correlates of the neuromusculature of the pharynx, haptor and reproductive tracts were explained. The results implicated acetylcholine, FMRFamide-related peptides (FaRPs) and serotonin in sensory and motor function. The results were compared with those of the monogeneans Macrogyrodactylus clarii and M. congolensis inhabiting the gills and skin respectively of the same host fish C. gariepinus.

Neuromusculature of Macrogyrodactylus congolensis, a monogenean skin parasite of the Nile catfish Clarias gariepinus

Phalloidin fluorescence technique, enzyme cytochemistry and immunocytochemistry, in conjunction with confocal scanning laser microscopy, were used to describe the neuromusculature of the monogenean skin parasite Macrogyrodactylus congolensis from the Nile catfish Clarias gariepinus. The body wall muscles are composed of an outer layer of compactly arranged circular fibres, an intermediate layer of paired longitudinal fibres and an inner layer of well-spaced bands of diagonal fibres arranged in two crossed directions. The central nervous system consists of paired cerebral ganglia from which three pairs of longitudinal ventral, lateral and dorsal nerve cords arise. The nerve cords are connected at intervals by many transverse connectives. Both central and peripheral nervous systems are bilaterally symmetrical and better developed ventrally than laterally and dorsally. Structural and functional correlates of the neuromusculature of the pharynx, haptor and reproductive tracts were examined. Results implicate acetylcholine, FMRFamide-related peptides and serotonin in sensory and motor function. The results were compared with those of Macrogyrodactylus clarii, a gill parasite of the same host fish C. gariepinus.

Neuromusculature of Macrogyrodactylus clarii, a monogenean gill parasite of the Nile catfish Clarias gariepinus in Egypt

Phalloidin fluorescence technique, enzyme cytochemistry and immunocytochemistry in conjunction with confocal scanning laser microscopy have been used for the first time to describe the nervous and muscle systems of the viviparous monogenean gill parasite, Macrogyrodactylus clarii. The gross spatial arrangement of muscle and associated cholinergic, peptidergic and aminergic innervations has been examined. The central nervous system (CNS) consists of paired cerebral ganglia from which emanate three pairs of longitudinal ventral, lateral and dorsal nerve cords, connected at intervals by transverse connectives. The CNS is better developed ventrally than dorsally or laterally, and has the strongest reactivity for all neuroactive substances examined. Structural and functional correlates of the neuromusculature of the pharynx, haptor and reproductive tracts have been examined. Results implicate acetylcholine, FMRFamide-related peptides (FaRPs) and serotonin in sensory and motor function in this monogenean, although confirmatory physiological data are obviously required.

Development of a cell culture system from the ovarian tissue of African catfish Clarias gariepinus

A growth medium with Leibovitz-15 L-15.as the base, supplemented with foetal bovine serum 10% vrv., fish muscle extract 10% vrv., prawn muscle extract 10% vrv., lectin concanavalin A. 0.02 mg mly1., lipopolysaccharide 0.02 mg mly1., glucose D 0.2 mg mly1., ovary extract 0.5% vrv.and prawn haemolymph 0.5%. has been formulated with 354"10 mOsm for the development and maintenance of a cell culture system from the ovarian tissue of African catfish, Clarias gariepinus. For its subculturing, a cell dissociationrextracting solution, composed of equal portions of trypsin phosphate versene glucose TPVG. containing 0.0125% wrv.trypsin and 25% vrv.non-enzymatic cell dissociation solution 1 and 2, has also been developed with which the cell culture can be passaged 15 times after which they cease to multiply and consequently perish. The cell cultures can be maintained for 12–15 days without fluid change between the passages. This is the first report of a cell culture system from the ovarian tissues of African catfish

Structure and vascularization of the ventricular myocardium of Piaractus mesopotamicus and Clarias gariepinus (Teleostei)

The structural characteristics of the ventricular myocardium and the arterial distribution of the ventricular wall were studied in two freshwater teleost fish species (Piaractus mesopotamicus and Clarias gariepinus). The ventricular myocardium consists of two distinct layers, an external compact layer and an internal spongy layer. In Piaractus mesopotamicus the compact layer contains fibres with an external longitudinal arrangement and an internal circular arrangement. The arterial vascularization of the compact layer is provided by subepicardial vessels and their ramifications in both species.

Morphological studies on the heart ventricle of African catfish (Clarias gariepinus)

The histological and ultrastructural characteristics of the heart ventricle in Clarias gariepinus (African catfish) has been studied by light microscopy and transmission electron microscopy. The ventricle of the heart has a saccular shape and the myocardial wall consists of an outer thin compact myocardium and an inner well-developed spongy myocardium. The myocardial layer has small myocytes, interstitial spaces and blood vessels. The myocytes are the major constituents of the ventricular wall. They are long cells, with large nuclei, and predominantly euchromatin. The sarcoplasmic reticulum of the ventricular myocytes consists of a network of tubules and subsarcolemmal cisternae oriented mainly along the longitudinal axis of the myofibrils. In contrast to the ventricular structure of other fish species described in the literature (Greer-Walker et al., 1985 Santer, 1985 Sanchez-Quintana et al., 1995, 1996), the African catfish, a freshwater sedentary fish recently introduced in neotropical climatic environments, showed a saccular ventricle that consisted of two muscle layers, a thin compact layer with large vessels and a developed spongy layer. The ultrastructure of the ventricular myocardium of C.gariepinus is similar to that of other teleosts, inclusive that of fish with other swimming habits.

Cardiorespiratory responses to hypoxia in the African catfish, Clarias gariepinus (Burchell 1822), an air-breathing fish

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)