Dietary composition and aspect of reproductive biology (fecundity and sex ratio) of African carp was investigated for 12 months. Specimens were collected from artisenal fishermen, measured for Length (cm) and weight (g), examined for genital papilla in the male and the stomach removed for food analysis. The main food categories were crustaceans, rotifers, insects, worms, plant parts and mud. The index of relative importance (IRI) values indicated that 13 out of the 21 food items were major diet components. The prominence of detritus in the diet indicated that L. coubie is a bottom feeder and is euryphagus. Fifty eight (58) 28.6% out of the 205 females had matured gonads. Absolute fecundity ranged from 679 to 15073 eggs. The relative fecundity ranged from 40 to 793eggs/ Length (cm) and 64 to 286 eggs/ weight (g). Spawning was between the months of May through August. The Length-Weight yielded significant results for female than male indicating that, females were in better condition than the males. The overall sex ratio of L. coubie was 1:1.67 in favour of females. The wide food range and high fecundity made L. coubie suitable for pond culture. @ JASEM
Our knowledge of the consumption of plankton by fish is still fragmentary. Trophic links between fish and plankton are often loose because plankton is a changing assemblage of pelagic organisms of valuable nutritional value. The objectives of the study were to determine the distribution and diversity of planktons in the fish ponds. Water samples for plankton analysis were collected monthly (January-December), along with water samples used for the determination of physico-chemical parameters in 250 ml bottles in Ponds 1, 2 and 5. The freshwater sample was mixed gently and pipetted into 5 ml plankton chamber containing 2 drops of Lugol's solution. The Lugol's solution which served as fixative also enhanced sedimentation of the organisms and was left overnight before analyzing plankton using Zeiss inverted plankton microscope and plankton determination keys. Data was analyzed using Shannon-Weaner diversity index, species richness, means and analysis of varians (ANOVA). The results showed that the highest species richness for dry season phytoplankton value of 27 was recorded in Pond 2, with the highest Shannon-Weaner diversity index value of 0.5401 in pond 5. Merismopaedia elegans with 3,434 in pond 2 was the most abundant phytoplankton species and chlorophyceae the most dominant taxa. The rainy season zooplankton species richness values (5 in pond 2) were higher than that of the dry season (3 in pond 3) with the highest Shannon-Weaner index value of 0.3501 recorded in pond 1. The most abundant zooplankton species Asplanchna species 57 was recorded in pond 2. Significant differences (p < 0.05) was observed for phytoplankton and zooplankton species between the ponds. Physico-chemical parameters had influence on the distribution and diversity of planktons in the fish ponds.
The study aimed to estimate the length weight relationship, condition factor and gut content of Chrysichthys furcatus a commercial important food fish in Obubra, central Cross River State. Monthly samples were collected for six month between May to October 2014. During the period a total of 187 specimens comprising of 125 females and 62 males were collected. The length -weight frequency distribution shows a total length ranged of 16 cm-60 cm and weight 50 g-549 g. The female fish have the highest length and weight frequency distribution except at weight ranged of 50 g-99 g where the males were more. Both sexes exhibited negative allometric growth pattern with an increased in length resulting to increase in weight of the fish. The condition factor (k) decreased with increased in the size of fish, why July and August recorded the least monthly condition factor. About 102 (54.55%) stomachs had some degree of food items in their guts with medium size specimens having the highest number of stomachs with some degree of food than small and large respectively. A total of 7 major categories with 27 food items comprising of animals, plants and detritus materials were identified. The sum total of 3,486 prey item with Cyclops (531) 15.24% constituting the most encountered while coleopteran (10) 0.29% was the least encountered prey. The most occurred prey item was detritus (100%) and Cyclops (98.12%) while the least coleopterans 3.67% with sand grains (11.44%) constituting the bulks of the gut content. The index of relative importance (IRI) reveals that Cyclops (1736.72), keretela (1394.82), tublex (1251.06), crustacean (1238.33) and crustacean eggs (1238.33) were the important and preferred prey item in the guts of C. furcatus. The ability of fish to capitalize on any available food items in the environment (euryphagous) is an important characteristic of culturable fish species. This implies that C. furcatus have brighter prospects for culture in ponds and proper species management and sustainability.
The study was designed to investigate the sub-lethal effects of paraquat on haematological parameters and histopathology of the gills, skin and liver of Clarias gariepinus juveniles of mean weight (38.26±1.20g) and length (17.50±1.55cm). The fish were exposed to 10, 20, 30, 40 and 50% of the 96hrsLC50 value of 107mg/l estimated from the 96 hours acute toxicity test. Blood samples were collected into heparinized tubes for the analyses of some haematological parameters, while the gills, skin and liver were also removed for histological examinations following standard procedures. The result revealed a significant reduction (P < 0.05) in the values of red blood cells (RBCs), haemoglobin (Hgb), packed cell volume (PCV) and erythrocytes indices from the control. The white blood cells (WBCs) and platelets (Plt) were however increasing significantly (P < 0.05) from those of the control as the test concentrations increased. The histology of the gills revealed some alterations such as epithelial proliferation, vacuolation of the mucus, hyperplasia of epithelial tissue of the gill filament, lifting and necrosis of the secondary lamellae. The exposed skin showed mucous cell proliferation, erosion of the epithelial lining, hypertrophy, necrosis of epithelial cells and widening of the epidermal and dermal layers. The liver exhibited cellular proliferation, sinusoid enlargement, congestion of the central vein, paranchymatous degeneration, vacuolar degeneration, pyknotic nucleic degeneration, legions and necrosis with severity as concentration of paraquat increases. The gills and skin were observed to be the most affected tissues in this study. The study also revealed that paraquat was toxic to C. gariepinus and causes some haematological and histopathological alterations in the fish blood and tissues at concentrations higher than 30mg/l. Therefore, the use of paraquat by farmers should be regulated particularly in area close to the aquatic environment.
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