Synodontis

Abstract: While the modern freshwater fish fauna of Africa has been the subject of considerable biological attention, there are few studies on the biogeography that include recent fossil reports. Since the publication of comprehensive reviews of Cenozoic freshwater fish faunas in Africa by Greenwood in the mid 1970s and updates in the late 1970s by Van Couvering, considerable collection and reporting of Cenozoic Africa fish has occurred. These specimens and reports have provided a considerable database from which to derive zoogeographical and biogeographical inferences. A pan-African fish fauna can be documented at the generic level throughout the Miocene in northern, central and eastern Africa, including Protopterus, Polypterus, Labeo, Alestes/Brycinus, Clarias/Heterobranchus, Synodontis, and Lates. The extinct genus Semlikiichthys (formerly Lates) may also be included in this pan-African fauna. Where the Miocene fish records were widely distributed through much of the African continent and were primarily fluvial-derived faunas, the Early Pliocene record is strictly a central and eastern one, mainly from lacustrine deposits. These reflect the new lacustrine habitats created through severe tectonic change, in the form of rifting and volcanism. The Pliocene faunas are characterised both by extinct taxa not previously recorded, and by immigrant taxa. By the Pleistocene the Rift systems were completely formed. However, ongoing volcanism and tectonics continued to alter the hydrological systems. In the Early and Middle Pleistocene, Lakes Albert and Edward both still had the widespread modern genera Lates and Synodontis, and several taxa known from previous deposits. However, all extinct taxa had disappeared, except Sindacharax (Characidae), which was still found in Lake Edward. In the Turkana Basin, there is continuity of most taxa from the Pliocene (except for Semlikiichthys, which is absent), as well as Miocene and Pliocene Sindacharax species. In the Middle Pleistocene, Sindacharax disappears from the African fossil record. Also, in the Pleistocene, several hydrological systems lose their pan-African faunas, including Lake Edward, Lake Victoria and the Maghreb. The modern faunas are not as diverse at the family level as previously. This history of the Neogene African fish fauna is necessarily incomplete without fossil records from many regions of Africa, particularly in the west and south.

Abstract: An 8-month survey of the Upper Zambezi River, its associated floodplain and marginal upland habitats yielded 16 catfish (Siluriformes) species, among which Schilbe intermedius comprised over half of the 3534 specimens. Generally catfishes were most abundant in floodplain and river channel habitats, but three species (Clariallabes platyprosopos, Synodontis macrostoma, S. nigromaculatus) were most abundant in the river channel, and three species (Amphilius uranoscopus, Chiloglanis neumanni, Leptoglanis rotundiceps) were most abundant or restricted within small tributary streams. Diet analysis revealed low pairwise dietary overlaps, but there was no statistically significant pattern of community-wide niche segregation based on prey type. The 16 catfishes fell into four size/trophic guilds: large carnivores (Clarias gariepinus, C. ngamensis), medium-sized carnivores (C. stappersii, C. theodorae, Parauchenoglanis ngamensis, Clariallabes platyprosopos, Schilbe intermedius), medium-sized omnivores (Synodontis leopardinus, S. nigromaculatus, S. woosnami, S. sp. cf. woosnami), and small omnivores (S. macrostigma, S. macrostoma, Amphilius uranoscopus, Chiloglanis neumanni, Leptoglanis rotundiceps). No evidence of reproductive activity was detected in any of the catfishes during the survey period of falling and low water conditions. Although catfishes are not as highly valued for food as cichlid fishes, three species are significant components of local commercial and subsistence fisheries: the two large Clarias by virtue of their size, and Schilbe by virtue of its great abundance. Abundances of the heavily exploited Clarias gariepinus and C. ngamensis stocks appear to be lower in the Upper Zambezi compared with the Okavango floodplain system.

Abstract: Within Enugu and Anambra States, Nigeria, identification of fishes has been based on morphological traits and do not account for existing biodiversity. For DNA barcoding, assessment of biodiversity, conservation and fishery management, 44 fish sampled from Enugu and Anambra States were isolated, amplified and sequenced with mitochondrial cytochrome oxidase subunit I (COI). Twenty groups clustering at 100% bootstrap value including monophyletic ones were identified. The phylogenetic diversity (PD) ranged from 0.0397 (Synodontis obesus) to 0.2147 (Parachanna obscura). The highest percentage of genetic distance based on Kimura 2-parameter was 37.00 ± 0.0400. Intergeneric distances ranged from 15.8000 to 37.0000%. Congeneric distances were 6.9000 ± 0.0140–28.1000 ± 0.0380, with Synodontis as the existing synonymous genus. Confamilial distances in percentage were 16.0000 ± 0.0140 and 25.7000 ± 0.0300. Forty-two haplotypes and haplotype diversity of 0.9990 ± 0.0003 were detected. Nucleotide diversity was 0.7372, while Fu and Li’s D* test statistic was 2.1743 (P 0.10) and nucleotide frequencies were C (17.70%), T (29.40%), A (24.82%), G (18.04%) and A + T (54.22%). Transitional mutations were more than transversions. Twenty species (99–100%) were identified with the e-value, maximum coverage and bit-score of 1e−43, 99–100 and 185–1194, respectively. Seventeen genera and 12 families were found and Clariidae (n = 14) was the most dominant among other families. The fish species resolution, diversity assessment and phylogenetic relationships were successfully obtained with the COI marker. Clariidae had the highest number of genera and families. Phylogenetic diversity analysis identified Parachanna obscura as the most evolutionarily divergent one. This study will contribute to fishery management, and conservation of freshwater fishes in Enugu and Anambra States, Nigeria.

Abstract: Although there are some reports on parasites of fish at different locations on River Niger, there had been no report for Illushi. Parasitological investigation of 71 fish samples belonging to 14 genera from river Niger at Illushi showed a 60.6% prevalence infection and an infection rate of 59.15%. The gills, stomach and sometimes muscles were infected; no parasites were found infecting the liver and eye lens. Nematodes, acanthocephalans, trematodes and cestodes were recovered in decreasing order of abundance. Proteocephalus sp. was found in Ctenopoma kingsleye and was the only parasite infecting Tilapia galilaeus. Diphyllobothrium sp. was only found in the stomach and gills of Chrysichthys nigrodigitatus. Paramphistomum sp. was the only trematode found in the gills of examined fishes. Bucephalus sp was only found in Synodontis eupterus and Distichodus engycephalus. Acanthocephalans were represented by Pomporhynchus, Quadrigidae and Neoechinorhynchus. Neoechinorhynchus was found only on the intestine of Lates niloticus. Parasites were more prevalent in fish of10 - 30cm standard length. There was no specific trend in parasite prevalence in S. eupterus, S. clarias, C. nigrodigitatus and C. kingsleye as regards the weight classes. The study showed the intestine as the preferred organ for infection, no infection was noticed in the oesophagus. (Journal of American Science 2010;6(3):16-21). (ISSN: 1545-1003).