Some haematological changes in hybrid catfish (Heterobranchus longifilis x Clarias gariepinus) fed different dietary levels of raw and boiled jackbean (Canavalia ensiformis) seed meal

Changes were observed in some haematological parameters of juvenile hybrid catfish (Heterobranchus longifilis x Clarias gariepinus) fed raw and 60 min-boiled jackbean seed meal (JBSM) at different dietary levels for 56 days. The haematocrit (packed cell volume, PCV), red blood cell (RBC) count, white blood cell (WBC) count and haemoglobin (Hb) concentration decreased significantly (P<0.05) with increasing dietary JBSM level. Though the mean values of the blood parameters of fish fed diets containing boiledJBSM (PCV = 29.93%; RBC = 1.2 x 106 mm-3; WBC = 15.91 x 103 mm-3; Hb = 8.31 g/100 ml) showed significant improvement when compared with those fed raw JBSM diets (PCV = 28.68%; RBC = 1.13 x 106 mm-3; WBC = 14.63 x 103 mm-3; Hb = 8.31 g/100 ml) they were, however, lower and significantly (P<0.05) different from those fed the control diet (PCV = 35.50%; RBC = 1.43 x 106 mm-3; WBC = 20.42 x 103 mm-3; Hb = 10.62 g/100 ml). However the observed reduction of the blood parameters did not go below the normal range of values recorded for catfish. Further investigation to improve the quality ofboiled JBSM is suggested

Effects of jackbean seed meal on the intestinal mucosa of juvenile Heterobranchus longifilis

Juvenile Heterobranchus longifilis were fed diets that were isonitrogenous (CP 30%) and isocaloric (ME 2900 Kcal/kg) comprising the control diet without jackbean seed meal (JBSM) and those containing raw and 60 min boiled JBSM at different inclusion levels. At the conclusion of the 56 days feeding study, histological examination of the intestinal mucosa of H. longifilis indicated that those fed the control diet remained normal. However, progressive damage to the epithelial mucosa of H. logifilis intestines was observed with increasing dietary level of JBSM. While fish fed diets with 10% fishmeal substituted by raw JBSM showed minor degeneration of the intestinal mucosa, those fed with 100% fishmeal substituted by raw JBSM showed severe damage. Boiling JBSM however moderated the adverse effect of high dietary JBSM since fish fed diet with 80% fishmeal substituted by boiled JBSM showed only early signs of mucosal degeneration. The findings suggest that boiled JBSM could be used to substantially replace fishmeal in fish diets with no negative effect on fish intestinal mucosa. This development impacts positively on fish production by reducing the cost of fish feed given the comparatively lower cost of JBSM with respect to fishmea

Parasitic infestation of Synodontis batensoda (Rüppell, 1832, Siluriformes, Mockokidae) at Rivers Niger-Benue Confluence, Nigeria

The Mockokid, upside down catfish, Synodontis batensoda caught with various fishing gears were studied for parasites for a period of 12 months (March 2007 to February 2008) in Rivers Niger and Benue at the Confluence. Out of 84 fish specimens examined, 61 (72.6%) fish hosts were infected, while 23 (27.4%) were uninfected. The total parasites recovered were 1196, comprising one protozoan ciliate (Trichodinids), two Digeneans (Allocreadim ghanensis and Metacercariae of Pygidiopsis genata), four Cestodes (Monobothrioides woodlandi, Bothriocephalus acheilognathii, Proteocephalus largoploglotis and Caryophyleus sp.), six Nematodes (Procamallanus laevionchus, Rhabdochona congolensis, Spinitectus guntheri, Oxyuris equi, Contracaecum microcephalum, Strongylides sp and larval Nematodes) and the Acanthocephalans (Acanthocephalus sp., Neoechinorhynchus prolixum and Acanthella sp. - the immature stages). Acanthocephalans had the highest prevalence among the parasites recovered. All parasites were recovered from the intestines except the Trichodinids which were recovered from the gills and skin of fish hosts. The relationship of host weight and parasite infection showed infection was highly significant (p < 0.01) in fish of larger weight of 76 to 100 g and above. There was no significant (p > 0.01) difference between the male and female fish hosts, both being equally infected. Multiple infections were recorded in several fish hosts, an indication of the rich parasitic fauna of the localities. This study provides an overview of parasites of S. batensoda in Rivers Niger and Benue at the Confluence.Keywords: Parasites, protozoan, helminths, nematodes, cestodes, acanthocephalans, Synodontis batensoda, Rivers Niger-Benue Confluence, NigeriaAfrican Journal of Biotechnology Vol. 12(20), pp. 3029-303

The daily weight gain, growth rate and length-weight relationships of Clarias gariepinus, Heterobranchus longifilis and their reciprocal hybrids (Pisces: Clariidae) reared under ambient environmental conditions

A comparative study was conducted on some growth parameters of Clarias gariepinus, Heterobranchus longifilis and their reciprocal hybrids in laboratory aquaria. This was aimed at determining the best aquaculture candidate amongst them. The growth parameters compared were: The condition indices, specific growth rates, average daily weight gain as well as their length-weight relationships. The four fish-types studied were contained, each type, in one of four different aquarium tanks which had equivalent ambient physico-chemical conditions. In terms of growth in length, the Clarias gariepinus♂ X Heterobranchus longifilis♀ hybrid (Cg ♂ X Hl♀), had the highest final length and weight (4.20 cm, 1.13 g ) while Clarias gariepinus (Cg) had the least ( 2.58 cm, 0.22 g). Heterobranchus longifilis (Hl) and the Clarias gariepinus ♀ X Heterobranchus longifilis ♂ hybrid (Cg♀ X Hl♂ ) had growth values falling between these two extremes (3.33 cm, 0.57g; 3.50 cm, 0.70 g) respectively. There was, however, no significant difference (P ˃ 0.05) between these values although a regression analysis of the length-weight relationships in the four fish-types revealed a significant positive correlation between fish length and fish weight. With respect to the condition indices, Cg had 1.10; Hl,1.12; Cg♀ X Hl♂, 1.14 and Cg ♂ X Hl♀, 1.17 (P ˂ 0.05). For specific growth rates (G%), Cg had 5.50% which was the least specific growth rate recorded amongst the fish-types studied while the Cg ♂ X Hl♀ hybrid had the highest, (8.44%). The other fish-types had values falling in between these two. There was also no significant difference between them, (P ˃ 0.05). With respect to the average daily weight gain, Cg still had the least value (0.06g) while the Cg ♂ X Hl♀ hybrid had 0.14 g, being the highest value.Hl had 0.12 g and Cg♀ X Hl♂ had a value of 0.13 g. No significant difference was recorded between them (P ˃ 0.05). In all cases, however, the face values obtained for the Cg ♂ X Hl♀ hybrid were always the highest and those of Cg, always the least. These results have been discussed.Key words: Weight gain, specific growth rate, length-weight relationships, condition indices, catfish hybrids, ambienc

Diseases and Mortalities of Fishes and Other Animals In the Gulf of Mexico

Most mortality results from natural causes including red tide which is primarily restricted to West Florida and cold-kills that have greater influence in the warmer regions of South Texas and South Florida, but also kill a significant amount of fish and other animals in the northern Gulf. With the exception of red tide and other harmful algal blooms, the health of the Gulf has not been systematically studied. Mexico has only recently started to evaluate the health of its coastlines. Mortalities of marine animals, particularly fishes, in the Gulf caused by natural and anthropogenic events seem to interact with infectious disease agents and noninfectious diseases, but the mortalities are often attributed to the disease agents alone. “Events” that cause mortalities include eutrophication; hypoxia; algal blooms; temperature, salinity, and weather extremes; and chemical and sediment pollution. “Diseases” include those caused by infectious agents, parasites, neoplasms, and developmental abnormalities. Interactions of the effects of diseases and stressful events are considered important but little investigated