Search Results (11)

Aquaculture has become a crucial component of global food production, yet catfish (10.8% of global finfish production) breeding programs often lack sufficient genetic data to fully utilize their production potential. In the last 15 years, there have been improvements in this field as two high-density (HD) single nucleotide polymorphism (SNP) arrays (250K and 690K) and low-density panels have been developed for North American channel catfish (Ictalurus punctatus) and blue catfish (Ictalurus furcatus). This lack of genomic tools hinders genetic improvement efforts in other commercially relevant catfish species besides them. Therefore, this review investigated the reason behind the lack of SNP chip usage in genetic-based selections in most catfish breeding programs and the cross-species applicability of the already existing high-density SNP arrays for genotyping members of the Clariidae, African catfish (Clarias gariepinu), and Siluridae, European catfish (Silurus glanis), families. This paper systematically reviews the literature of more than 16 SNP arrays, with 66 non-target species, and assesses the possibility of adapting catfish SNP arrays to the catfish families of interest. With lowered filtering (e.g., MAF > 0) thresholds, the Affymetrix Axiom 250K and Axiom Catfish 690K Genotyping Array could potentially be used on important market species like African and European catfishes. In the long term, chip development would be the solution for these species, but, until then, cross-application is a viable alternative. Despite low polymorphic SNPs (~1%) and call rates (~0%), this SNP array could aid researchers and breeders, improving catfish aquaculture and management. Full article

In the late Cenozoic, the south-west of Eastern Europe was a region affected by extensive hydrological transformations that resulted in the retreat of the Eastern Paratethys and the emergence and further evolution of freshwater communities. In recent decades, a relatively rich fossil actinopterygian fauna has been described from this area. The present study was based on previous systematic studies and aimed to assess and trace the temporal dynamics of the diversity of fish assemblages that existed in the area from the Late Miocene until the end of the Pleistocene. Species diversity, taxonomic diversity, taxonomic complexity, and functional diversity were analysed. It was found that the diversity of the fish assemblages notably decreased during the Late Miocene, when representatives of the families Clariidae, Moronidae, Sciaenidae, and Gobiidae disappeared, and remained relatively low during the Pliocene. During the Pleistocene, however, functional diversity gradually increased, despite fluctuating species and taxonomic diversity and taxonomic richness and complexity, which suggests an increasing stability of the coenotic structure within the fish communities. The revealed temporal trends reflect the impact of the palaeoenvironmental and palaeoecological processes that characterised the region during the late Cenozoic, particularly orogenic and climatic changes, and the evolution of a typical limnophilous, lacustrine-riverine fish fauna. Full article

In the Upper Congo Basin, there are few records of monopisthocotylan parasites from clariids. More surveys of clariid fishes can lead to the discovery of multiple monopisthocotylan species that are new to the region or new to science. We aimed to investigate the monopisthocotylan parasite fauna belonging to Quadriacanthus of five clariid fishes in the Upper Congo Basin by (i) inventorying the species composition and providing the description of new species when necessary, and (ii) analysing their infection parameters. Clarias ngamensis, C. stappersii, C. buthupogon, C. gariepinus and C. theodorae were purchased from fishermen in the Lufira, Lubumbashi and Kafubu rivers in the Upper Congo Basin. Monopisthocotylans were mounted on glass slides with ammonium picrate-glycerin for identification based on morphological analysis of genital and haptoral sclerotised parts. Eight species, namely Q. aegypticus, Q. allobychowskiella, Q. amakaliae, Q. domatanai, Q. halajiani, Q. kalomboi n. sp., Q. bassocki n. sp. and Q. shigoleyae n. sp. are reported. The most prevalent parasite species was Q. amakaliae on C. stappersii (prevalence 60%) with a mean infection intensity of 9.8 ± 7.7. We report C. stappersii and C. buthupogon as new hosts for species of Quadriacanthus as well as three new parasite species for science and new localities for the first five parasite species mentioned above. The new records and the description of Q. kalomboi n. sp., Q. bassocki n. sp. and Q. shigoleyae n. sp. increase the knowledge of the diversity of monopisthocotylans in this region. Full article

A parasitological study carried out in May 2022 and March 2023 in the Nyando River of Lake Victoria Basin, Kenya, disclosed two parasitic lernaeid copepods: Lamproglena cleopatra Humes, 1957, from the gills of a cyprinid, the Ningu Labeo victorianus Boulenger, 1901, endemic to the Lake Victoria drainage system, and Lamproglena clariae Fryer, 1957, from a clariid, the North African catfish Clarias gariepinus (Burchell, 1822). The copepods were studied and supplementary taxonomic information was presented using scanning electron micrographs and genetic data. Scanning electron microscopy (SEM) provided information on the morphology of L. cleopatra’s antennae, oral region, thoracic legs (2–5), and furcal rami not previously reported. Analyses of the partial fragments of 18S and 28S rDNA and cytochrome c oxidase subunit 1 (cox1) of the two parasites showed them to be distinct from all other Lamproglena taxa retrieved from GenBank. This study presents new taxonomic information on morphology using SEM and provides the first ribosomal (18S and 28S rDNA) and mitochondrial (mtDNA) data for these two parasite species. The cox1 data provided are the first for all 38 nominal species of Lamproglena. Notably, the study also provides a new host record for L. cleopatra and extends the geographical information of this species to Kenya. Full article

The airbreathing walking catfish (Clariidae: Clarias) comprises 32 species that are endemic to African freshwater systems. The species-level identification of this group is challenging due to their complex taxonomy and polymorphism. Prior to this study, the biological and ecological studies were restricted to a single species, Clarias gariepinus, resulting in a biased view of their genetic diversity in African waters. Here, we generated the 63-mitochondrial Cytochrome c oxidase subunit 1 (COI) gene sequences of Clarias camerunensis and Clarias gariepinus from the Nyong River in Cameroon. Both C. camerunensis and C. gariepinus species maintained adequate intra-species (2.7% and 2.31%) and inter-species (6.9% to 16.8% and 11.4% to 15.1%) genetic distances with other Clarias congeners distributed in African and Asian/Southeast Asian drainages. The mtCOI sequences revealed 13 and 20 unique haplotypes of C. camerunensis and C. gariepinus, respectively. The TCS networks revealed distinct haplotypes of C. camerunensis and shared haplotypes of C. gariepinus in African waters. The multiple species delimitation approaches (ABGD and PTP) revealed a total of 20 and 22 molecular operational taxonomic units (MOTUs), respectively. Among the two Clarias species examined, we found more than one MOTU in C. camerunensis, which is consistent with population structure and tree topology results. The phylogeny generated through Bayesian Inference analysis clearly separated C. camerunensis and C. gariepinus from other Clarias species with high posterior probability supports. The present study elucidates the occurrence of possible cryptic diversity and allopatric speciation of C. camerunensis in African drainages. Further, the present study confirms the reduced genetic diversity of C. gariepinus across its native and introduced range, which might have been induced by unscientific aquaculture practices. The study recommends a similar approach to the same and related species from different river basins to illuminate the true diversity of Clarias species in Africa and other countries. Full article

The mitogenome of an endemic catfish Clarias camerunensis was determined from the Cameroon water. This circular mitogenome was 16,511 bp in length and comprised 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNAs, and a single AT-rich control region. The heavy strand accommodates 28 genes, whereas the light strand is constituted by ND6 and eight transfer RNA (tRNA) genes. The C. camerunensis mitochondrial genome is AT biased (56.89%), as showcased in other Clarias species. The comparative analyses revealed that most of the Clarias species have 6 overlapping and 11 intergenic spacer regions. Most of the PCGs were initiated and terminated with the ATG start codon and TAA stop codon, respectively. The tRNAs of C. camerunensis folded into the distinctive cloverleaf secondary structure, except trnS1. The placement of the conserved domains in the control region was similar in all the Clarias species with highly variable nucleotides in CSB-I. Both maximum likelihood and Bayesian-based matrilineal phylogenies distinctly separated all Clarias species into five clades on the basis of their known distributions (South China, Sundaland, Indochina, India, and Africa). The TimeTree analysis revealed that the two major clades (Indo-Africa and Asia) of Clarias species might have diverged during the Paleogene (≈28.66 MYA). Our findings revealed the separation of Indian species (C. dussumieri) and African species (C. camerunensis and Clarias gariepinus) took place during the Paleogene, as well as the South Chinese species (Clarias fuscus) and Sundaland species (Clarias batrachus) splits from the Indochinese species (Clarias macrocephalus) during the Neogene through independent colonization. This pattern of biotic relationships highlights the influence of topography and geological events in determining the evolutionary history of Clarias species. The enrichment of mitogenomic data and multiple nuclear loci from their native range or type locality will confirm the true diversification of Clarias species in African and Asian countries. Full article

The ichthyofauna of Lake Tanganyika consists of 12 families of fish of which five belong to Siluriformes (catfishes). Studies on Siluriformes and their parasites in this lake are very fragmentary. The present study was carried out to help fill the knowledge gap on the monogeneans infesting the siluriform fishes of Lake Tanganyika in general and, more particularly, Clarias gariepinus. Samples of gills of Clarias gariepinus (Clariidae) were examined for ectoparasites. We identified the monogenean Gyrodactylus transvaalensis (Gyrodactylidae). This is the first time this parasite was found infecting gills. We are the first to observe a large spine in the male copulatory organ of this species and to provide measurements of its genital spines; this completes the description of the male copulatory organ, which is important in standard monogenean identification. This is the first monogenean species reported in C. gariepinus at Lake Tanganyika and the third known species on a representative of Siluriformes of this lake. It brings the total number of species of Gyrodactylus recorded in Lake Tanganyika to four. Knowing that other locations where this species has been reported are geographically remote from Lake Tanganyika, we propose a “failure to diverge” phenomenon for G. transvaalensis. Full article

The present study was carried out to analyse the effect of water temperature on two components: (1) growth performance, and (2) gastric emptying time (GET) of African catfish Clarias gariepinus fingerlings. After 70 days, it was observed that experimental temperatures had no significant effects on the growth performance parameters, except for food conversion ratio (FCR) and food conversion efficiency (FCE). GET observation through X-radiography denoted that the shortest GET (10 h) was observed in fish reared at 32 °C and the longest GET (16 h) was observed in fish reared at 26 °C. The rapid digestion rate coincides with the FCR and FCE obtained in this study. Considering the limited scope of our study, more extensive studies on the impact of water temperature on other fish physiological parameters should be pursued. A better understanding of this research topic would be beneficial for the growth of African catfish fingerling aquaculture. Full article

In the present study, a possible nature immunostimulant and growth promoter—humic substances (HS) originating from Siberian leonardite mineraloid—were tested on juvenile Clarias gariepinus performance. Feed additive was applied onto commercial pelleted feed at four HS levels—0, 1, 3, and 6% w/w (HS0, HS1, HS3, HS6, respectively). Diets were tested in five repetitions (in total, n = 1800 individuals, mean body weight 28.1 ± 6.2 g) for 56 days. Growth and production parameters, fish condition and somatic indices, and overall mortality were evaluated after 14, 28, 42, and 56 days of exposure. Whereas, plasma samples were collected only after 0, 28, and 56 days, when fish health status was assessed with biochemical parameters (total proteins, TP; alanine aminotransferase, ALT; aspartate aminotransferase, AST; lactate dehydrogenase, LDH; cholesterol, CHOL; triglycerides, TAG) and fish antioxidant status with glutathione (reduced glutathione, GSH; oxidized glutathione, GSSG; glutathione ratio GSH/GSSG). Although a significantly positive effect of HS feed additive on growth performance was not found in the present study, moderately positive effects were found regarding biochemical parameters (ALT, AST, LDH, CHOL, and TAG) and antioxidants (GSH/GSSG ratio) that were improved especially in the HS3 group. Full article

Accessory respiratory organs (AROs) are a group of anatomical structures found in fish, which support the gills and skin in the process of oxygen uptake. AROs are found in many fish taxa and differ significantly, but in the suborder Anabantoidei, which has a labyrinth organ (LO), and the family Clariidae, which has a dendritic organ (DO), these structures are found in the suprabranchial cavity (SBC). In this study, the SBC walls, AROs, and gills were studied in anabantoid (Betta splendens, Ctenopoma acutirostre, Helostoma temminckii) and clariid (Clarias angolensis, Clarias batrachus) fishes. The histological structure of the investigated organs was partially similar, especially in relation to their connective tissue core; however, there were noticeable differences in the epithelial layer. There were no significant species-specific differences in the structure of the AROs within the two taxa, but the SBC walls had diversified structures, depending on the observed location. The observed differences between species suggest that the remarkable physiological and morphological plasticity of the five investigated species can be associated with structural variety within their AROs. Furthermore, based on the observed histology of the SBC walls, it is reasonable to conclude that this structure participates in the process of gas exchange, not only in clariid fish but also in anabantoids. Full article

Human pressures and loss of natural fish habitats led to a decline in fish populations in terms of abundances, biodiversity, and average size in sub-Sahelian Burkina Faso. Little knowledge exists about fish assemblages regarding their composition, their habitat preferences, or their sensitivity to or tolerance of human pressures. This research provides the first data-driven basis for sustainably managing fish and associated aquatic and terrestrial habitats. Surveys in four different regions sampled 18,000 specimens from 69 species during the dry season. Fish communities, available abiotic habitat conditions, habitat use, and human pressures were assessed and analyzed. Fish communities cluster into four distinct types, each dominated by either Cichlidae, Clariidae, Cyprinidae, or Alestidae and accompanied by specific other families and genera of fish. Habitat preferences of four key species (Labeo coubie, Bagrus bajad, Chelaethiops bibie, and Lates niloticus) were linked to ecological habitat conditions. Results show that physical parameters influence fish community composition and abundances and, when indexed according to pressure type, are linked to responses in fish metrics. Relative abundance either dropped (Mormyridae) or increased (Cichlidae, Cyprinidae) with rising pressure intensity, and some sentinel taxa (Auchenoglanis, Hydrocynus) were only found in low-pressure sites. The outcomes of this study provide basic knowledge of habitat availability, habitat use by fish, species associations, and human pressures and therefore provide the basis for effective conservation and management of fish populations. Full article