Bioassay using the water soluble fraction of a Nigerian Light Crude oil on Clarias gariepinus fingerlings

Summary: A 96-hour bioassay was conducted using the water soluble fraction of a Nigerian light crude oil sample on Clarias gariepinus fingerlings. 0, 2.5, 5.0, 7.5 and 10 mls of water soluble fractions (WSF) of the oil were added to 1000 litres of de-chlorinated tap water to form 0, 25, 50 , 75 and 100 parts per million representing treatments 1 to 5 respectively. Each treatment had two replicates with fifteen fish per replicate. At the end of the 96-hour period of exposure, the fish were transferred into separate bowls containing fresh water without oil for recovery for ten more days. Heavy metal and total hydrocarbon contents of the water and fish were analyzed at 96 hour and 14 days which marked the end of the recovery period. No mortalities were recorded on all treatments during the 96-hour period. Mortalities were observed between 120 and 144 hours after the onset of the experiment with the maximum number of dead fish (p<0.05) from treatment 5(100 ppm WSF) during the recovery period indicating a delayed response to the WSF by the fish. No mortalities were recorded after 144 hours till the termination of the experiment at 14 days . The 96-hour LC50 could not be calculated since no deaths occured during the period. The Total hydrocarbon contents of the water were 0, 0.026 ,0.316 ,0.297, 0.253 mg/l for treatments 1(0 ppmWSF)) to 5(100ppmWSF) respectively. Lead , iron and cadmium were not detected in water during the study, lead was also not detected in fish muscles from all treatments. The iron contents of all the treatments were lower than the control except for treatment 3(50 ppm WSF). THC concentrations in fish were higher at 96 hours and 14days than in the water indicating bioconcentration in fish and a retention in the fish long after exposure.Keywords: WSF, C.gariepinus , Toxicity , Heavy metals , THC,Bioconcentratio

PRESENCE OF HYDROCARBONS AND HEAVY METALS IN SOME FISH SPECIES IN THE CROSS RIVER, NIGERIA

The study was undertaken to determine the total hydrocarbon (THC) and heavy metal contents of fish (finfish and shellfish) in the Cross River, Nigeria. Fish Samples were collected in the dry (March) and rainy (October) seasons between 2000-2002. The finfish species identified in the study were Synodontis clarias, Sarotherodon galilaeus, Heterotis niloticus, Schilbe mystus, Parachanna obscura, Citharinus citherus, Mormyrus rume, Phago loricatus and Petrocephalus ansorgii and the shellfish were Macrobrachium vollenhovenii and Tympanotonus fuscatus. Significant differences (P< 0.05) existed between finfish and shellfish in both THC and heavy metals contents. The levels of THC in fish exceeded the World Health Organization's limit of 0.0001 ppm by an average of 3.2 and 15.57 mg/kg in fin and shellfish respectively. High concentrations of vanadium and THC in fish samples were the main indicators of pollution from petroleum sources. Key Words: THC, heavy metals, finfish, and shellfish, Cross River, Nigeria. African Journal of Livestock Extension Vol.3 2004: 90-9

The protective effect of walnut (Tetracarpidium conophorum) leaf and onion (Allium cepa) bulb residues on the experimental Pseudomonas aeruginosa infection in Clarias gariepinus juveniles

The study assessed the effect of Walnut Leaf (WL) and Onion Bulb (OB) residues on disease resistance of Clarias gariepinus juveniles against infection with the bacteria pathogen Pseudomonas aeruginosa. Clarias gariepinus juveniles were fed with diets containing 0 (control), OB2 (0.5%), OB3 (1.0%), OB4 (1.5%), OB5 (2.0%), WL6 (0.5%), WL7 (1.0%), WL8 (1.5%) and WL9 (2.0%). Biochemical (serum total protein, albumin, globulin, albumin: globulin ratio) and haematological indices of the fish were investigated. Fish were exposed to 0.5ml of 107 Pseudomonas aeruginosa of 24h old culture with the percentage mortality and relative level of protection recorded for 4 weeks post – infection. The results demonstrated that the fish fed with treated diets showed increased in biochemical and haematological indices (P&lt;0.05) compared with the control. The challenge infection showed an improvement from treated groups with percentage mortalities and relative level of protection highest in WL8 (3.33%, 90%) and OB2 (3.33%, 90%) and least (33.33%, 0%) in control respectively. The results suggest that walnut leaf residue at 1.5% inclusion for one month could be a potential, less expensive and promising dietary supplement that would positively affect growth, haematology and make C. gariepinus more resistant to Pseudomonas aeruginosaKeywords: Pseudomonas aeruginosa, Clarias gariepinus, Onion bulb, Walnut leaf Mortality, Haematolog

The Effect of Walnut (Tetracarpidium Conophorum) Leaf and Onion (Allium Cepa) Bulb Residues on the Tissue Bacteriological Changes of Clarias Gariepinus Juveniles

In this study, the effect of walnut leaf (WL) and onion bulb (OB) residues on tissue bacteriology of Clarias gariepinus juveniles by dietary intake was investigated. Nine experimental diets: control (0%), OB2 (0.5%), OB3 (1.0%), OB4 (1.5%), OB5 (2.0%), WL6 (0.5%), WL7 (1.0%), WL8 (1.5%) and WL9 (2.0%) were formulated and replicated thrice at 40% crude protein. Fish (mean weight 7.4&#177;0.02g) were fed twice daily at 3% body weight for 12 weeks. Microbiological analyses of water and fish (skin, gill, intestine and liver) and organ index (liver, spleen, kidney and heart) were investigated. Data were analysed using descriptive statistics and ANOVA at p=0.05. Results of enterobacteriacea and total viable count from this study revealed that bacterial loads on the water and fish of the experimental tanks were more affected by A. cepa and T. conophorum than the control for 4, 8 and 12 weeks and were significantly different (P&lt;0.05) from the control. The values decreased in treated groups as the levels of inclusion (0.5%, 1.0%, 1.5% and 2.0%) increased and as the months increased. Also, organ index showed that the liver, heart, kidney and spleen were not significantly increased in all the treated groups and the control. The results suggest that walnut leaf and onion bulb residues inclusion in the diet of Clarias gariepinus could be a potential, less expensive and promising dietary supplementation that would positively influence growth, reduce and prevent bacterial infections in fish culture.La pr&#233;sente &#233;tude a examin&#233; l&#8217;effet d&#8217;un apport alimentaire de r&#233;sidus de feuilles de noyer (WL: walnut leaf) et de bulbes d&#8217;oignon (OB: onion Bulb) sur la bact&#233;riologie des tissus de Clarias gariepinus juv&#233;niles. Neuf r&#233;gimes exp&#233;rimentaux - t&#233;moin (0%), OB2 (0,5%), OB3 (1,0%), OB4 (1,5%), OB5 (2,0%), WL6 (0,5%), WL7 (1,0%), WL8 (1,5% ) et WL9 (2,0%) - ont &#233;t&#233; pr&#233;par&#233;s et r&#233;p&#233;t&#233;s trois fois avec une teneur en prot&#233;ines brutes de 40%. Des poissons (poids moyen 7,4 &#177; 0,02 g) ont &#233;t&#233; nourris &#224; 3% du poids corporel deux fois par jour pendant 12 semaines. Des analyses microbiologiques de l&#8217;eau et des poissons (peau, branchies, intestin et foie) ont &#233;t&#233; effectu&#233;es, et l&#8217;indice d&#8217;organes (foie, rate, reins et coeur) a &#233;t&#233; &#233;tudi&#233;. Les donn&#233;es ont &#233;t&#233; analys&#233;es &#224; l&#8217;aide de statistiques descriptives et de l&#8217;ANOVA &#224; p = 0,05. Les r&#233;sultats du d&#233;nombrement des enterobact&#233;riac&#233;es et le total des comptages viables de cette &#233;tude ont r&#233;v&#233;l&#233; que les charges bact&#233;riennes sur l&#8217;eau et les poissons des bassins exp&#233;rimentaux ont &#233;t&#233; plus affect&#233;es par A. cepa et T. conophorum par rapport au groupe t&#233;moin pendant 4, 8 et 12 semaines et &#233;taient significativement diff&#233;rentes (P &lt;0,05) de celles du groupe t&#233;moin. Les valeurs ont diminu&#233; dans les groupes trait&#233;s au fur et &#224; mesure de l&#8217;augmentation des niveaux d&#8217;inclusion (0,5%, 1,0%, 1,5% et 2,0%) et des mois. De plus, l&#8217;indice d&#8217;organes a montr&#233; que le foie, le coeur, les reins et la rate n&#8217;avaient pas significativement augment&#233; de volume, que ce soit dans tous les groupes trait&#233;s ou le groupe t&#233;moin. Ces r&#233;sultats portent &#224; croire que l&#8217;inclusion de r&#233;sidus de feuilles de noyer et de bulbes d&#8217;oignons dans le r&#233;gime alimentaire de Clarias gariepinus pourrait &#234;tre envisag&#233;e comme une suppl&#233;mentation alimentaire potentielle, moins co&#251;teuse et prometteuse, capable d&#8217;avoir une influence positive sur la croissance, de r&#233;duire et de pr&#233;venir les infections bact&#233;riennes dans l&#8217;&#233;levage de poissons.Mots-cl&#233;s: charge microbienne; feuille de noyer; bulbe d&#8217;onion; Clarias gariepinus; bact&#233;rie

Preliminary evaluation of some aspects of the ecology (growth pattern, condition factor and reproductive biology) of African pike, Hepsetus odoe (Bloch 1794), in Lake Eleiyele, Ibadan, Nigeria

Abstract A preliminary investigation of length-weight relationship, condition factor and reproductive ecology of African pike fish, Hepsetus odoe, was conducted between June to August 2010 in Lake Eleiyele. A total of 90 samples of the fish species were caught by fishermen using gill nets. The results obtained showed that fish species had isometric growth pattern (contrary to negative allometry expected) with the growth exponent, b value of 2.64, that is not statistically different from 3 and with high statistical power of 0.866 when tested. The mean condition factor, K, was found to be 2.6, indicating that the fish species were in good condition in the study area. For reproductive biology, mean fecundity and gonadosomatic index were found to be 1349 eggs and 3.53% respectively. This study was necessary to fill the knowledge gap and provide information for management and conservation of the investigated species in the lake system. This study recommended that further research needs to be conducted because the sampling was carried out in the rainy season period and within a quarter of a year