Channa Obscura Research Articles

Incidence of Heavy Metals (Pb, Cu, Zn) in Fish Species in Afikpo North Local Government Area of Ebonyi State

This study was conducted to evaluate the concentration of lead, copper and zinc on the gills, viscera and muscle parts of three fish species- Clarias gariepinus, Channa obscura, and Tilapia zilli from Uwana river in Afikpo in Ebonyi State, Nigeria. Lead concentrations did not differ significantly (p > 0.05) among the fish species and were 0.025 ± 0.045 ppm in C. gariepinus, 0.024 ± 0.041 ppm in C. obscura and 0.036 ± 0.056 ppm in T. zilli. However copper was significantly (p T. zilli 0.067 ± 0.116 ppm compared to C. gariepinus 0.033 ± 0.038 ppm and C. obscura 0.030 ± 0.041 ppm. Zinc concentrations were similar (p > 0.05) in the 3 fish species of C. gariepinus (0.454 ± 0.256 ppm), C. obscura (0.518 ± 0.246 ppm), and T. zilli (0.514 ± 0.279 ppm). Gills (0.026 ± 0.044 ppm), Viscera (0.029 ± 0.051 ppm) and Muscle (0.030 ± 0.048 ppm) did not differ significantly (p > 0.05) in lead content but viscera contained more copper (0.084 ± 0.114 ppm) compared to the gills (0.035 ± 0.039 ppm) and muscle (0.011 ± 0.013 ppm). Significant differences (p < 0.05) were observed in the zinc contents of the body parts as Gills contained more zinc (0.590 ± 0.209 ppm) compared to viscera (0.0567 ± 0.291 ppm) and muscle (0.329 ± 0.188 ppm). In all cases, the heavy metal concentrations in the fish species were lower than the maximum limit set by FAO/WHO/ FEPA.

Quality Assessment of Edible Fish Species at Flood Basin of Omambala River, South East Nigeria

Background: Food poisoning resulting from microbial and heavy metals pollution is commonplace. These contaminants do not only reduce the nutritional value of the food but are in many cases toxic. In this study, the proximate composition, bacterial quality and some heavy metals (Cd, Pb, Hg) concentration in three common fish species (Claria gariepinus, Heterobrachus bidorsalis and Channa obscura) found in flood basin of Omambala River in Anambra, Nigeria were evaluated from 2016 to 2017. Methods: Wet digestion was used for the samples preparation and AOAC methods were adopted for the proximate analysis. Standard aerobic pour-platetechniques were used for bacterial enumeration while heavy metal concentrations were determinedusing Atomic Absorption Spectrophotometer (AAS). Results: All the fish species had high protein, moisture, lipid, ash and minerals contents. Mean bacteria count of 3.36x106cfu/g was observed in C. gariepinus while C. obscura had mean bacterial count of 3.23x106cfu/g and H. bidorsalis had mean bacterial count of 3.40x106cfu/g. C. gariepinus had a cadmium and lead concentration of 0.012±0.012mg/kg,and 0.0043±0.0012mg/kg respectively while C.obscura had 0.010 ± 0.005mg/kg and 0.037 ±0.013mg/kg of cadmium and lead. H.bidorsalis had 0.011 ± 0.002mg/kg, and 0.048 ± 0.005mg/kg of cadmium and lead respectively. Conclusion: All the fish species are good sources of nutrient. The microbial and heavy metals concentrations were within the acceptable international limits for heavy metals in foods. However, the presence of these toxicants in the samples is a source of concern in relation to the health of the consumers.

Length-Weight Relationship of Some Fish Species in a Tropical Rainforest River in South-East Nigeria

Abstract The Length-Weight relationship of some fish species from Oramiri-Ukwa River, was studied from January to December, 2014. The slope (b) values obtained in the nine species ranged from 1.830 to 5.670 with most of the fishes indicating a negative allometric growth pattern except for Papyrocranus afer, with b value of 3.04, thus showing a positive isometric growth pattern. The following fish species showed a high degree of positive correlation at (P &gt; 0.05); Ctenopoma kingselyae, Alestes imberi, Channa obscura, Oreochromis niloticus, Tilapia mariae, Tilapia zillii, Synodontis omais, and Papyrocranus afer. Chrysichthys auratus did not show this positive correlation. The condition factor (K) of the fish species ranged from 0.99 to 4.54, indicating that most of the fish were in good condition except for Chrysichthys auratus with 0.99.

Distribution of three non-essential trace metals (Cadmium, Mercury and Lead) in the organs of fish from Aiba Reservoir, Iwo, Nigeria

The distribution of non-essential trace elements in some vital organs of 11 fish species from Aiba Reservoir, Iwo, Nigeria was assessed between November 2010 and June 2011. The fish species belong to seven families; family Mormyridae, family Cyprinidae, family Hepsetidae and family Channidae each with one species; family Bagridae and family Clariidae each with two species; and family Cichlidae with three species. All families, except Clariidae and Channidae, are common in the daily catch from the reservoir. Atomic absorption spectrophotometry was used to determine the levels of cadmium, mercury and lead in fish organs. The concentration of toxic trace metals in fish ranged from 0.001 to 0.100ppm (Cd), 0.000–0.067ppm (Hg) and 0.001–0.125ppm (Pb) dry weight. This study shows similarity (p>0.05) in the distribution of Cd, Hg and Pb among fish species; and a non-uniform distribution of toxic trace metals within fish organs with Kidney>Liver>Gill≥Intestine≥Muscle. Canonical variate analysis shows clear discrimination of Clarias macromystax and Channa obscura for gill trace metal levels of Cd, Hg and Pb while Labeo senegalensis and Oreochromis niloticus were discriminated for liver trace metal values of Cd and Pb only when compared to other fish species studied. The discrimination of some fish species based on trace metals in the gills and liver suggests different regulatory strategies for trace metal accumulation. Variation due to comparison among different fish species from the same water body suggests that accumulation may be species dependent. Differential accumulation of toxic trace metals in fish organs makes them good bioindicators of freshwater contamination.

Aspects of the Ecology of the Grass Mat Finfish Community of Kugbo Creek in Niger Delta, Nigeria

A study on the grass-mat finfish community of Kugbo Creek was done in 3 zones of Kugbo Creek for 24 months. Biweekly samples obtained from the zones showed a total of 3192 individual finfish belonging to 26 species and 14 families. Occurrence among zones was 25 species were found in freshwater zone 1, 24 in fresh/brackish water zone 2 and 4 species in brackish water zone 3 respectively. The dominant finfish species was Dormitator pleurops with 451 individuals. The habit host rear species of Nannocharax niloticus, Karibia karibensis, Thysia ansorgii, Marcrousenius thuysi and Mastacablus loennbergi. Juveniles of Calamoichthys calabaricus, Heterotis niloticus, Channa obscura, Polycentropsis abreviata, Heterobranchus longifilis and Mastaceblus loennbergi, were also caught in the habit. This shows that some fish undergo part of their developmental stages in the grass mat habitat, including some with high commercial values. Some species such as Gymnacus niloticus and Hepsetus odoe build their spawning nest in the grass mat where they lay eggs during breeding season. Virtually all other fresh water fish species also visit the habitat either in search of food or shelter at one time or the other as most stomach content compositions are also found in the grass mat habitat, e.g. Papyranocranus afar and Xenomystus nigri, . The habitat sheltered endangered finfish species such as Neolebias powelli, that was caught during sampling. These suggest the importance and sensitive nature of the

Microflora of fresh and smoke-dried fish in Yenagoa metropolis, Nigeria

The microbial load of fresh and smoke-dried fish marketed in Yenagoa metropolis was evaluated. The samples were three fish types: Clarias angularis, Channa obscura andChrysicthtys auratus from Tombia and Swali markets were analysed. The bacterial counts for fresh fish samples ranged from 4.0 x 108 - 2.30 x 1010 cfu/g while fungal counts ranged from 1.8 x 104 - 7.0 x 104 cfu/g. Bacterial and fungal counts for smoked fish were lower, ranging from 1.8 x 104 - 2.5 x 108 cfu/g and 1.0 x 104 - 4.0 x 105 cfu/g respectively. Twelve (12) bacterial isolates were obtained from fresh fish samples and 13 isolates from smoked fish. The isolated bacteria belonged to the genera Bacillus, Pseudomonas, Proteus, Staphylococcus, Streptococcus, Corynebacterium, Lactobacillus and Klebsiella. Bacillus was the most predominant with a frequency of occurrence of 50 and 58.8% for fresh fish and smoked fish respectively. The fungi isolates belonged to Aspergillus, Rhizopus, Penicillium, Saccharomyces and Fusarium species. The most predominant fungi were Aspergillus spp and Penicillium spp which constituted 23.0 and 15.4% for fresh fish and smoked fish respectively. Key words: Fish, Microflora, smoke-dried fish.

Mineral composition of some marine and freshwater fishes

The mineral composition of four marine fishes: Katsuwonus pelamis, Scomber scombrus, Trachurus trachurus and Genyonemus lineatus obtained from a local market in Lagos, Nigeria and ten freshwater fishes: Heterotis niloticus, Auchenoglanis occidentalis, Heterobranchus bidorsalis, Channa obscura, Lates niloticus, Mormyrus rume, Oreochromis niloticus, Sarotherodon galilaeus, Tilapia zillii and Micraletes acutidens obtained from a reservoir in Ilorin, Nigeria were studied. The mineral content was determined using the Atomic spectrophotometer (model 420). The results showed that the dietary minerals present in both freshwater and marine specimens were: manganese, copper, iron, zinc, potassium, calcium, magnesium and phosphorus. Phosphorus content was low in the freshwater fishes. The Fishes studied are good sources of dietary minerals especially iron and copper.

Instrumental Neutron Activation Analysis of Total Halogen and Extractable Organohalogen in Fish Samples from the Densu Basin

ABSTRACTInstrumental Neutron Activation Analysis (INAA) has been validated and the method applied to determine total halogen and extractable organohalogen in six fish species namely Heterotis niloticus, Channa obscura, Hepsetus odoe, Tilapia zilli, Clarias gariepinus, and Chrysichthys nigrodigitatus. The samples were collected directly from the fishermen at their landing sites from the two sampling towns, Weija and Nsawam along the Densu river basin in the Greater Accra Region of Ghana. The concentrations of total chlorine, bromine, and iodine analysed by INAA were between 770.70 - 1123.50 mg/kg, 8.00 - 25.00 mg/kg and 0.70 - 4.20 mg/kg respectively. For the extractable organohalogens concentrations ranged from 0.30 – 350.40 mg/kg. The highest concentration of 350.40 mg/kg was obtained for extractable organochlorine (EOCl) in Hepsetus odoe sampled from Nsawam, while the lowest concentration was obtained for extractable organoiodine. The content of extractable organohalogen were in the order of EOCl>> EOBr > EOI. Key words: Neutron activation, Organohalogen, Fish species, Densu basin, Extractable.

The food and feeding habits of five freshwater and brackish-water fish species in Nigeria

The food and feeding habits of five economically important fresh-and brackish-water fishes, Channa obscura, Chrysichthys nigrodigitatus, Heterotis niloticus, Synodontis nigrita and Trachinotus maxillosus, were investigated. A number of techniques were used to carry out gut content analysis, including the Hynes 'point' system based on volume estimations expressed as relative percentages. Juveniles of C. nigrodigitatus were omnivorous, consuming 32% gastropods, 30% nematodes, 14% diatoms and 8% crustaceans, while adults were planktotrophic, consuming 23% diatoms, 33% Chlorophyceae and 22% crustaceans. Synodontis nigrita juveniles fed almost exclusively (91%) on nematodes, while adults were predominantly planktotrophic, their diet comprising 50% diatoms and 50% crustaceans. Trachinotus maxillosus was exclusively benthotrophic, consuming 99.5% gastropods and 0.46% nematodes. Heterotis niloticus was planktotrophic at the adult stage and consumed 72% crustaceans, 12% gastropods, 3% fish and about 90% planktotrophic at the juvenile phase. Chrysichthys obscura was purely benthotrophic at the juvenile stage, feeding 100% on nematodes, but fed mainly (89%) on fish at the adult stage.

Ichthyofaunal survey of rivers within Ewekoro cement manufacturing operational areas

A total of 298 fish specimens belonging to seven families were caught during ichthyoplanktonic survey of three rivers within the Ewekoro cement facility catchment area located in southwestern Nigeria. The highest numbers of specimens were caught from Alaguntan (37.0%) and Elebute (36.6%) rivers while 28.9% of the fish samples were collected from Itori River. The fish population and species diversity recorded in the catchment rivers were significantly lower (p < 0.05) than comparative catches from Ewekoro River located about 30 km downstream of the factory operational area. The food items ingested by the specimens across the seasons in the catchment rivers revealed obvious differences in diet with some degree of overlap in the fish trophic preferences. However, the omnivorous species dominated the catches in each of the rivers, irrespective of season. Categorization of the fish specimens based on habitat-related adaptive physiology showed that a significant number of the fish from Alaguntan and Itori Rivers have accessory respiratory organs. The four species with accessory respiratory organs were Polypterus senegalus Curv., Clarias gariepinus C. & V., Ctenopoma kingslayae Gun. and Channa obscura Smith. Of the 12 fish species recorded in the Ewekoro cement facility catchment rivers, only P. senegalus, C. gariepinus, C. obscura and Oreochromis niloticus (Trew.) are valuable food fishes in southwestern Nigeria.

A preliminary investigation into the fisheries potentials of Doma Lake, Nasarawa State, Nigeria

A preliminary investigation into the fisheries potentials of Doma Lake in Nasarawa State, Nigeria was carried out from July to December 2000. Values of physico-chemical parameters (temperature, pH, dissolved oxygen, total alkalinity and free carbon dioxide) did not vary significantly (P > 0.05) between the sampling months. A total of 8 families made up of 11 genera and 16 species of fish were recorded in the lake. The family Cichlidae (67.56%) dominated while the family Hepsetidae was the least (0.45%). Length-weight regression analysis showed that six species of fish (Gnathonemus niger, Channa obscura, Hepsetus odoe, Oreochromis niloticus, Tilapia monodi and Tilapia zilli) exhibited positive allometric growth. Barilius niloticus showed negative allometric growth while Hemichromis bimaculatus showed isometric growth pattern. The mean standard length and weights of most of the species of fish correlated strongly except that of Barilius niloticus, which correlated weakly. The condition factor (K) showed that the smaller sized fishes thrived better in the lake. There were more male than female fish in the lake. Gnathonemus niger exhibited the highest fecundity while the lowest fecundity was observed in Hemichromis fasciatus and Tilapia zilli. The implications of the findings are discussed. Key Words: Fisheries potentials, Doma Lake, Nigeria Journal of Aquatic Sciences Vol.19(2) 2004: 59-64

Bacterial and helminth bioload of cultured &lt;i&gt;Channa obscura&lt;/i&gt; fish

An investigation of the bacterial and helminth fuana of organs of diseased and healthy African snake head fish (Channa obscura) from Nigeria Agip Green River project, River State, Nigeria was undertaken. The intestine, skin, fin, gill, tissue and liver of the fish were examined for both bacterial and helminth load. The results indicated that the bacterial load of the diseased fish samples were higher than those of the apparently healthy fish. Identification tests of the probable isolates revealed the isolation of the following genera: Aeromonas, Citrobacter, Enterobacter, Klebsiella, Lactobacillus, Pseudomonas, Campylobacter, Proteus, Serratia, Staphyloccocus, Yersinia and Vibro sp. Whereas helminth fauna isolated were Camallanus sp., Capillaria sp., Acetodoxtra sp., Chimostomum sp, Diphostomum sp. and Polyonchobethium sp. Percentage helminth infestation was found to be higher in adults than sub-adults and juveniles, while the percentage prevalence of the helminth infections amongst the fishes examined was found to be 41%. Helminth infection therefore varies amongst age groups. This study reveals the bacteria and load of cultured Channa obscura Key words: Bioload, helminths, Bacteria, Cultured fish Journal of Aquatic Sciences Vol.18(2) 2003: 93-100

Cruising specialists and accelerators – Are different types of fish locomotion driven by differently structured myosepta?

Locomotor specialists, such as accelerators and cruisers, have clearly differing body designs. For physical reasons these designs are mutually exclusive, i.e. cruisers necessarily have poor accelerating capabilities and vice versa. For the first time, we examine whether differences in the anatomy of the musculo-tendinous system of the trunk are present in addition to the differences in external body design. We investigated the myoseptal series of two closely related locomotor specialists, the cruiser Scomber scombrus and the accelerator Channa obscura, by microdissections combined with polarized light microscopy and histology. Our comparison includes 3D-morphology of myosepta, spatial arrangement and length of myoseptal tendons, their relation to red and white muscles, rostrocaudal changes in all these aspects and the musculo-tendinous system of the caudal fin. Regarding all these features, Channa has retained the plesiomorphic condition of its actinopterygian ancestor. In contrast, the derived morphology of Scomber is characterized by (i) lateral (LT) and myorhabdoid tendons (MT) that are lengthened to up to 20% of body length (compared to a maximum of 8.2% in Channa), (ii) posterior myoseptal cones that are subsequently linked by horizontal projections of merged LTs and MTs, (iii) an increased area of red muscle fibers that insert to LTs of myosepta, (iv) the reduction of epineural (ENTs) and epipleural tendons (EPTs) that connect backbone and skin, (v) specific caudal tendons that are identified to be serial homologues of LTs and MTs of more anterior myosepta, (vi) and a partial reduction of intrinsic caudal muscles. These results suggest the following functional adaptations in the cruiser Scomber. Red muscle forces may be transmitted through LTs and posterior cones to the prominent tendons of the caudal fin. The length of LTs and the intersegmental connections along the posterior cones may facilitate posterior force transmission and may be correlated with the long propulsive wavelength generally observed in cruising carangiform swimmers. Epineural and epipleural tendons are interpreted to minimize lateral backbone displacement during high body curvatures. This is consistent with the lack of these tendons in Scomber, because high body curvatures are not displayed in stiffer-bodied carangiform swimmers. It remains to be tested whether the specializations revealed in this initial study for Scomber represent general specializations of carangiform swimmers. Taking into account the geometry of myoseptal tendons and the horizontal septum we evaluate how local bending according to beam-theory can be generated by white or red muscle activity in Channa and Scomber. In both species, the musculo-tendinous anatomy of the caudal fin explains the functional asymmetry of the caudal fin that was experimentally revealed in previous studies.

The biology of snakehead, Channa obscura (Gunther), in a Nigerian pond under monoculture

Some aspects of the biology of Channa obscura (Gunther) based on small samples under monoculture are presented and discussed. The length-weight relationship indicated positive allometric growth. The mean somatic condition ( K′) was inversely related to standard length. The high percentage (75%) of empty stomachs and mean stomach fullness ranks showed poor feeding conditions. The fish feed provided was unsuitable; the fish depended on natural food items and exhibited cannibalism. The male-female ratio was 1:3. The fish were reproducing under culture conditions; the biphasic pattern of reproduction was seasonal. The fecundity was low, ranging from 35 to 4010 eggs; it was correlated neither to standard length nor body weight.

Fish communities in the eastern, seasonal-floodplain of the Sudd, Southern Sudan

Annual flooding of the permanent Sudd swamps innundates large areas of Oryza longistaminata grasslands. Fish migration into a southeast section of the seasonal floodplain was led by Clarias gariepinus, Polypterus senegalus and several small species which were intent on spawning. Channa obscura and juveniles of Oreochromis niloticus were prominent among later entrants. From a total of 23 species caught in seasonal habitats, 7 contributed over 97% of total estimated numerical and biomass densities. The latter ranged from 435–580 kg ha−1. In the 1982–83 flood-season entry to the floodplain was essentially restricted to species tolerant of oxygen-deficient waters and thereby able to penetrate the papyrus and Typha swamps of the permanent wetland. Migrants became stranded in temporary pools and subject to heavy cropping by birds.

Analyses of the stomach contents of the piscivorous fishes of the Upper Ogun River in Nigeria

The stomach contents of the fishes of the Upper Ogun River were scrutinised for three consecutive years. 8 out of the 36 species resident in the river are predominantly piscivorous. These are Mormyrops deliciosus, Hydrocynus forskahlii, Hepsetus odoe, Bagrus docmac, Lates niloticus and Hemichromis fasciatus. Piscivorous habits in Schilbe mystus and Eutropius niloticus are less developed. Three others, viz: Clarias lazera, Heterobranchus longifilis and Channa obscura, which were classified as piscivores by other workers, were caught. The stomachs of C. obscura examined were all empty while those of C. lazera and H. longifilis contained mainly aquatic invertebrates. The major prey of these piscivores are small sized Barbus spp. Other prey fishes include mormyrids, characids, cyprinids, citharinids, catfishes and cichlids. The relationships between the piscivorous and prey fishes and the partitioning of the available resources by these piscivores are discussed.

Water-line defence and gun-shields for cruisers

Locomotor specialists, such as accelerators and cruisers, have clearly differing body designs. For physical reasons these designs are mutually exclusive, i.e. cruisers necessarily have poor accelerating capabilities and vice versa. For the first time, we examine whether differences in the anatomy of the musculo-tendinous system of the trunk are present in addition to the differences in external body design. We investigated the myoseptal series of two closely related locomotor specialists, the cruiser Scomber scombrus and the accelerator Channa obscura, by microdissections combined with polarized light microscopy and histology. Our comparison includes 3D-morphology of myosepta, spatial arrangement and length of myoseptal tendons, their relation to red and white muscles, rostrocaudal changes in all these aspects and the musculo-tendinous system of the caudal fin. Regarding all these features, Channa has retained the plesiomorphic condition of its actinopterygian ancestor. In contrast, the derived morphology of Scomber is characterized by (i) lateral (LT) and myorhabdoid tendons (MT) that are lengthened to up to 20% of body length (compared to a maximum of 8.2% in Channa), (ii) posterior myoseptal cones that are subsequently linked by horizontal projections of merged LTs and MTs, (iii) an increased area of red muscle fibers that insert to LTs of myosepta, (iv) the reduction of epineural (ENTs) and epipleural tendons (EPTs) that connect backbone and skin, (v) specific caudal tendons that are identified to be serial homologues of LTs and MTs of more anterior myosepta, (vi) and a partial reduction of intrinsic caudal muscles. These results suggest the following functional adaptations in the cruiser Scomber. Red muscle forces may be transmitted through LTs and posterior cones to the prominent tendons of the caudal fin. The length of LTs and the intersegmental connections along the posterior cones may facilitate posterior force transmission and may be correlated with the long propulsive wavelength generally observed in cruising carangiform swimmers. Epineural and epipleural tendons are interpreted to minimize lateral backbone displacement during high body curvatures. This is consistent with the lack of these tendons in Scomber, because high body curvatures are not displayed in stiffer-bodied carangiform swimmers. It remains to be tested whether the specializations revealed in this initial study for Scomber represent general specializations of carangiform swimmers. Taking into account the geometry of myoseptal tendons and the horizontal septum we evaluate how local bending according to beam-theory can be generated by white or red muscle activity in Channa and Scomber. In both species, the musculo-tendinous anatomy of the caudal fin explains the functional asymmetry of the caudal fin that was experimentally revealed in previous studies.