Search Results (102)

Catfish is a major commercial and subsistence species in Malawi, making its sustainability vital for local livelihoods and food security. However, limited evidence exists on the long-term biological and economic depletion of commercial catfish stocks. This study assessed the depletion status of the catfish fishery in the southeast arm of Lake Malawi using secondary catch and effort data from 2000 to 2023 obtained from the Malawi Department of Fisheries, and price and cost data obtained from the field study. Applying the bioeconomic Gordon–Schaefer model, the study estimated biological depletion and economic depreciation to quantify resource losses and evaluate the fishery’s sustainability. Constant and periodic harvesting strategies were examined to determine sustainable harvest thresholds. Results show that depletion occurred in 15 of the 24 years analysed, with a cumulative biomass loss of 446.1 tonnes and an estimated total depreciation of about MK 1.5 billion. These findings indicate exploitation beyond sustainable levels both biologically and economically, threatening stock recovery, long-term productivity, and economic viability. The study highlights the value of bioeconomic modelling in fishery assessment and underscores the urgent need for improved management, including strengthened monitoring, effort regulation, and enhanced enforcement, to ensure sustainable utilisation of catfish resources and protect dependent livelihoods. Full article

Aquaculture sustainability in rapidly urbanizing regions is increasingly threatened by heavy metal contamination originating from complex anthropogenic land-use patterns. This study used an integrated model to evaluate the molecular-to-human health continuum in hybrid catfish (Clarias gariepinus × Clarias macrocephalus) sourced from Pathum Thani, Thailand’s primary aquaculture hub. We integrated geospatial land-use data with heavy-metal quantification, oxidative-stress biomarkers, and transcriptional profiling to assess how canal-specific water quality modulates fish health and consumer risk. The results revealed significant spatial heterogeneity in metal concentrations, corresponding to the province’s 27% urban–industrial land-use footprint. While water quality generally met regulatory limits, a pronounced aqueous–biotic discrepancy, “bioaccumulation paradox” was identified at certain sites, where muscle and hepatic tissues exhibited lead (Pb), chromium (Cr), and nickel (Ni) levels that substantially exceeded international safety standards. Biochemical and molecular analyses provided functional evidence of physiological distress, specifically significantly elevated malondialdehyde (MDA) levels, and the transcriptional modulation of cat, cyp1a, gpx, met, tnf, and star genes indicated that chronic metal exposure overwhelmed antioxidant defenses and induced potential endocrine disruption. Moreover, human health risk assessments revealed that the hazard index (HI) and target cancer risk (TR) exceeded unacceptable thresholds at multiple hotspots, indicating that Cr is a primary carcinogenic driver. These findings highlight a “GAP Paradox,” where farm-level certifications are insufficient to mitigate risks posed by the surrounding canal network. This study presents vital evidence-based risk profiles that necessitate a transition to a spatially based regulatory framework, incorporating geospatial land-use monitoring into national food safety policies to protect both aquaculture viability and public health. Full article

The African catfish (Clarias gariepinus) is an important aquaculture species in the Philippines, but it exhibits reproductive dysfunctions in captivity due to the absence of natural spawning cues and culture-induced stress. In hatcheries, sperm collection often requires sacrificing male breeders, limiting breeding program applications, and threatening genetic diversity. This study evaluated and optimized hormonal induction protocols to enhance spermiation and fertilization success in male C. gariepinus. Two experimental trials were conducted under controlled hatchery conditions. In Trial 1, human chorionic gonadotropin combined with a dopamine antagonist (hCG + DA; 5000 IU·kg⁻¹ BW + 5 mg·kg⁻¹ BW) and Ovaprim (1.0 mL·kg⁻¹ BW) significantly increased circulating testosterone and estradiol levels, spermiation index, and fertilization outcomes (embryo viability, hatching, and larval survival). In Trial 2, medium to low doses of hCG + DA (3000–5000 IU·kg⁻¹ BW + 5 mg·kg⁻¹ BW) and Ovaprim (0.75–1.0 mL·kg⁻¹ BW) yielded the best performance in terms of hormone levels, spermiation index, and fertilizing capabilities. The presence of a dopamine antagonist (DA) likely contributed to the efficacy of the treatments, since dopamine suppresses the secretion of gonadotropin-releasing hormone (dopaminergic inhibition), and DA counteracts this effect, increasing LH and FSH levels necessary for gametogenesis. Taken together, these results highlight the potential of optimized hormonal protocols to mitigate reproductive dysfunctions in male C. gariepinus in aquaculture settings. Further studies should refine dose combinations, assess the long-term health of broodstock, and evaluate cost-effectiveness to support sustainable broodstock management and genetic conservation. Full article

This study investigates the genomic basis of immune adaptation in the transparent glass catfish (Kv: Kryptopterus vitreolus), focusing on the loss of the Toll-like receptor 21 (TLR21) gene. Comparative genomic analysis with closely related non-transparent North African catfish (Cg: Clarias gariepinus) revealed 11 TLR genes in the latter, while only 8 TLR genes (KvTLR1, 2, 3, 5, 7, 9, 13, and 20) were retained in the glass catfish, with TLR21 specifically absent. Collinearity analysis confirmed that the genomic region containing TLR21 is conserved across eight siluriform species, with loss exclusively in the glass catfish, supporting its lineage-specific absence. Structural expansion was notable in KvTLR5, KvTLR7, and KvTLR20. Molecular docking indicated that binding stability between CpG oligonucleotides and TLR21 varies significantly, with CpG-B 1681 showing the strongest interaction, which highlights sequence-dependent ligand recognition. Interestingly, absence of the TLR1 gene in another transparent teleost, the X-ray tetra (Pristella maxillaris), suggests that transparent fishes may share an evolutionary trend of lineage-specific TLR gene loss. Together, these findings reveal a distinctive evolutionary trajectory in the innate immune receptor family of transparent fishes and provide new molecular insights into their adaptive immune strategies. These insights will benefit the academic community by improving comparative frameworks for fish innate immunity, and they may inform disease prevention and health management strategies in aquaculture and the ornamental fish trade. Full article

This study evaluated the performance of lettuce (Lactuca sativa) cultivated in coupled aquaponic systems integrated with Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) under tropical greenhouse conditions. The experiment was conducted across two consecutive lettuce production cycles to assess fish growth, plant performance, water quality, and nutrient dynamics. African catfish exhibited significantly higher specific growth rates (1.08 ± 0.18%/day; p = 0.02) and weight gain (92.38 ± 22.29%; p = 0.03) compared with tilapia. During the first lettuce cycle, tilapia-based systems yielded significantly higher final plant weights (177.6 ± 34.4 g/plant; p = 0.0002), and greater increases in leaf number, weight gain, and absolute growth rate than catfish-based systems. However, in the second cycle, catfish systems resulted in superior lettuce leaf morphology, with significantly greater leaf length, width, and total leaf area. Nutrient profiles differed markedly between systems. In the deep-water culture (DWC) units, total phosphorus (TP) concentrations were significantly higher in the tilapia-based system during cycle 1 (12.39 ± 0.64 mg/L; p = 0.0001), while total nitrogen (TN) concentrations were significantly higher in the catfish treatment during cycle 2 (21.54 ± 2.93 mg/L; p = 0.0007). Catfish-based systems also showed higher levels of calcium and sodium. Despite these differences, temperature, pH, and dissolved oxygen remained within optimal ranges for aquaponic production across both systems. Overall, tilapia-based aquaponics promoted faster early-cycle plant growth and higher initial yield, whereas catfish-based systems enhanced nitrogen availability and improved lettuce leaf structural development over successive cycles. These findings indicate that fish species selection plays a critical role in shaping nutrient dynamics and crop performance in tropical aquaponic systems. Full article

African catfish (Clarias gariepinus, AC) is one of the most widely farmed freshwater fish species in Central Europe. Processing operations generate up to 55% by-products (BPs), predominantly carcasses rich in proteins, lipids, and minerals. This study develops a comprehensive valorization process for ACBPs to recover gelatin, protein hydrolysate, fish oil, and pigments. The processing protocol consisted of sequential washing, oil extraction, demineralization, and biotechnological treatment to disrupt the collagen quaternary structure. A two-factor experimental design was employed to optimize the processing conditions. The factors included the extraction temperatures of the first (35–45 °C) and second fraction (50–60 °C). We hypothesized that enzymatic conditioning, combined with sequential hot-water extraction, would yield gelatin with properties comparable to those of mammalian- and fish-derived gelatins, while enabling a near-zero-waste process. The integrated process yielded 18.2 ± 1.2% fish oil, 9.8 ± 2.1% protein hydrolysate, 1.7 ± 0.7% pigment extract, and 25.3–37.8% gelatin. Optimal conditions (35 °C/60 °C) produced gelatin with gel strength of 168.8 ± 3.6 Bloom, dynamic viscosity of 2.48 ± 0.02 mPa·s, and yield of 34.76 ± 1.95%. Life cycle assessment (LCA) identified two primary environmental hotspots: water consumption and energy demand. This near-zero-waste biorefinery demonstrates the potential for comprehensive valorization of aquaculture BPs into multiple value-added bioproducts. Full article

Despite being banned since 1992, the organochlorine pesticide aldrin was recently detected in the Albasini Dam in Limpopo Province, South Africa. Aldrin is listed in the initial twelve persistent organic pollutants (POPs) and is rapidly broken down into dieldrin. Therefore, the presence of aldrin in the Albasini Dam indicates recent exposure and poses an environmental concern. Since 2006, a decline in fish numbers and adverse health effects have been reported in fish from the dam. This study aimed to investigate the potential effects of aldrin on the health of male African sharptooth catfish (Clarias gariepinus) through acute exposure to an environmentally relevant concentration of aldrin (0.14 µg/L) and an increased concentration (1.40 µg/L) under controlled laboratory conditions (28.7 °C; pH 8). The liver and kidney showed histological changes in both organs without significant differences between the groups for the 0.14 µ/L aldrin concentration. However, a significant difference was found in the kidney histological indices between the control fish and fish exposed to the high aldrin concentration (p = 0.014). A significant difference in kidney indices was observed between the two aldrin concentrations (p = 0.001). It was evident that histological changes in the kidney were prevalent and severe in fish exposed to 1.40 µg/L aldrin. This means that the observed levels of aldrin in Albasini Dam water (0.14 µg/L) may not pose a direct danger to the fish liver and kidney; however, as aldrin was banned for use, its presence in the dam is concerning, as at 1.40 µg/L, it may impair fish health. Full article

Effective fisheries management relies on accurate stock assessments to ensure sustainable exploitation and long-term ecosystem stability. Fisheries from the Nile Delta lakes of Egypt—comprising Manzala, Burullus, Edku, and Mariout—are economically critical, collectively contributing about 40% of the nation’s total capture fisheries and are facing severe anthropogenic challenges. This study assessed the stock status of 10 key fish species and two crustacean species from these four Nile Delta lakes by determining their life history parameters and exploitation levels. The analysis included estimation of the Length–Weight Relationship (LWR), von Bertalanffy Growth Function (VBGF) parameters, instantaneous mortality coefficients (Z, M, F), and the exploitation ratio (E). Asymptotic total length (L∞) varied widely, ranging from 10.47 cm for Portunus pelagicus to 86.78 cm for Clarias gariepinus (in Lake Manzala). The growth coefficient (K) spanned from 0.31 yr⁻¹ (C. gariepinus) to 1.79 yr⁻¹ (Metapenaeus stebbingi), reflecting diverse life history strategies. The key finding, based on the Gulland criterion, is that all commercial stocks examined in the Nile Delta lakes are currently subjected to severe overexploitation, with the exploitation ratio (E) consistently exceeding the optimal threshold of 0.5. These results underscore the urgent need for adaptive management strategies, including stricter gear regulations and improved fisheries monitoring, to ensure the sustainability of these vital resources. Full article

Nigeria’s aquaculture sector, which has been dominated by the production of African catfish (Clarias gariepinus), has held considerable potential to improve national food security, support livelihoods, and contribute to economic growth. Although Nigeria has been ranked among the world’s leading producers of farmed catfish, a persistent fish supply deficit that exceeds 2.5 million metric tons annually has been reported. This gap has been sustained by factors such as low productivity, genetic decline, inadequate hatchery systems, and limited export competitiveness. A comprehensive perspective is presented in this review, in which findings from recent researches, field surveys, and stakeholder consultations have been synthesized. The dominance of hybrid species such as Heteroclarias, which has been driven by consumer demand due to fast growth and large body size, is highlighted. Additionally, ecological and genetic concerns resulting from unregulated breeding are emphasized. Major systemic constraints, which include poor broodstock management, weak hatchery infrastructure, low technical capacity, and poor supply chain governance, have also been identified. A strategic approach involves modernizing fish breeding programs by developing a robust and active Fish Breeding Community of Practice (FCoP), enhancing physical infrastructure, improving data collection and management, standardizing germplasm exchange procedures, and increasing the number and capacity of fish breeders and technicians in breeding programs. Identifying traits preferred by farmers and end-users ensures that fish breeding is demand-driven and inclusive. Building capacity in genomic resources to implement an accurate predictive platform for performance assessment will significantly shorten the breeding cycle and increase the rate of genetic progress. This will be complemented by the adoption of modern aquaculture technologies, such as recirculating aquaculture systems, and the development of institutional frameworks for production, certification, and traceability schemes. Capacity development, which should be promoted through collaboration among academic institutions, industry actors, and government agencies, has been recommended. The alignment of aquaculture expansion with environmental sustainability, improved biosecurity, and habitat protection has been considered critical. By outlining strategies for innovation, investment, and policy reform, this review provides a roadmap through which Nigeria’s catfish industry can be transformed into a globally competitive and sustainable sector. Full article

Background/Objectives: North African catfish (Clarias gariepinus) and bighead catfish (Clarias macrocephalus) play crucial roles in Thai aquaculture. Although significant growth disparities exist among these species, the genetic factors underlying these differences are still unknown. This study aimed to identify GH1 gene polymorphisms, in North African and bighead catfish populations across Thailand and Laos. Methods: Sequencing, phylogenetic, and clustering analyses were performed to assess genetic diversity, selection patterns, and lineage differentiation of catfish partial GH1 fragment. Results: Six alleles of the studied fragment of GH1 gene were identified; they differed at 33 variable sites within intron 2, located between the conserved regions at the 3′ end of exon 2 and the 5′ end of exon 3. At the population-level, GH1 exhibited low heterozygosity (mean H_o = 0.043 ± 0.023; H_e = 0.059 ± 0.028). Bayesian clustering analyses identified two distinct genetic clusters, corresponding to North African and bighead catfish, apart from the bighead population in Laos, indicating their distinct genetic origins. Evidence of purifying selection was observed in both species. Phylogenetic analysis indicated the presence of lineage-specific alleles in the GH1 gene. Conclusions: These findings provide valuable insights into GH1 polymorphisms in commercially important catfish species and may help to develop future breeding programs aimed at enhancing aquaculture productivity. Full article

Background/Objectives: Understanding variabilities in the Major Histocompatibility Complex class I (MHC I) gene is essential for evaluating immunogenetic diversity in clariid catfish. MHC I plays a critical role in immune defense by presenting endogenous antigens to cytotoxic T cells. Therefore, we aimed to investigate the genetic diversity, selection patterns, and phylogenetic relationships of MHC I alleles in three important clariid catfish species (Clarias gariepinus, Clarias macrocephalus, and Clarias batrachus) across wild and hatchery populations in Thailand. Methods: Targeted next-generation sequencing of a 174 bp fragment partial exon 6 of MHC I-UAA gene was performed, along with phylogenetic analyses, neutrality tests and dN/dS analyses. Results: Overall, 91 novel alleles were identified in 674 individuals, all of which were novel (100% novelty), with none matching existing reference sequences, thereby revealing extensive variation in population-specific variants. Phylogenetic analyses revealed allele sharing among species, which was consistent with balanced selection. Neutrality tests and dN/dS analyses provided evidence of both purifying and diversifying selection, with episodic positive selection detected at multiple codon sites associated with the antigen-binding α1 domain. Distinct selection patterns among populations, influenced by local environmental conditions and human pressures, along with high allele richness, are reflected in the diversity of immunogenetic variations. Conclusions: These findings provide critical insights into immune adaptation and highlight the potential of MHC I as a functional marker for genetic monitoring. Although a causal relationship between MHC I polymorphism and disease resistance is debated, studies suggest associations with pathogen survival, indicating future implications for aquaculture breeding and conservation, particularly in marker-assisted selection for broodstock management in Thailand. Full article

In this study, the growth and welfare of the African catfish (Clarias gariepinus, Burchell 1822) were investigated under industrial farming conditions. For this purpose, the growing success (cm, g) and typical stress related parameters (glucose-, lactate-, cortisol-concentrations, growth hormone, HSI-liver index) were investigated on the African catfish (102–841 g) in relation to an external stressor (working light and noise) and different feeding regimes (day, night, and day and night feeding) over 83 days. As no significant effects were found among the experimental feeding treatments in relation to the growth performance and investigated stress parameters, the time of feeding seems to have less impact to the production success and stress reactions as suggested before. Regarding our results, the effect of feeding conditioning could have played a strong factor likewise the ageing process of the reared fish species which is known to be rather photophobic. Therefore, the factor of conditioning and its influence to the time shift in feeding regimes and the impact of noise and light stressors during feeding should be investigated separately in future experiments to obtain further results in this context and clarify the validity of the best feeding conditions for African catfish. Full article

Lactic acid bacteria (LAB) preserve many foods and play a vital role in fermented food products. This study designed a controlled biotechnological process of catfish (Clarias gariepinus) fermentation with a LAB starter culture isolated from corn hydrolysate. The BY (Barbu-Yelouassi) LAB strain was characterized regarding fermentative and antimicrobial potential, and its adaptability in the simulated gastrointestinal system (SGIS). After 10–12 h of cultivation on MRS broth (De Man Rogosa and Sharpe), the strain achieved the maximum exponential growth, produced maximum lactic acid (33.04%), and decreased the acidity up to pH 4. Also, the isolated strain showed increased tolerance to an acidic pH (3.5–2.0), high concentrations of salt (2–10%), and high concentrations of bile salts (≤2%). The behavior in SGIS demonstrated good viability after 2 h in artificial gastric juice (AGJ) (1 × 10⁷ CFU/mL) and up to 2 × 10³ CFU/mL after another 6 h in artificial intestinal juice (AIJ). The characterized BY strain was identified with the API 50CHL microtest (BioMerieux) as Lactiplantibacillus pentosus (Lbp. pentosus) (90.9% probability), taxon confirmed by genomic DNA sequencing. It was also demonstrated that Lbp. pentosus BY inhibited the growth of pathogenic bacteria, including Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and sporulated bacteria, such as Bacillus cereus. Additionally, it suppressed the sporulation of fungi like Aspergillus niger, Fusarium sp., and Penicillium sp. Furthermore, the Lbp. pentosus BY strain was used to ferment catfish, resulting in three variants of lanhouin (unsalted, with 10% salt, and with 15% salt), which exhibited good microbiological safety. Full article

The latest FAO report indicates that aquaculture accounts for 51% of the global production volume of fish and seafood. However, despite the continuous growth of this activity, there is evidence of the excessive use of groundwater in its production processes, as well as pollution caused by nutrient discharges into surface waters due to the water exchange required to maintain water quality in fishponds. Given this context, the objectives of this study were as follows: (1) to review which emergent and floating plant species are used in constructed wetlands (CWs) for the bioremediation of aquaculture wastewater; (2) to identify the aquaculture species whose wastewater has been treated with CW systems; and (3) to examine the integration of CWs with recirculating aquaculture systems (RASs) for water reuse. A systematic literature review was conducted, selecting 70 scientific articles published between 2003 and 2023. The results show that the most used plant species in CW systems were Phragmites australis, Typha latifolia, Canna indica, Eichhornia crassipes, and Arundo donax, out of a total of 43 identified species. These plants treated wastewater generated by 25 aquaculture species, including Oreochromis niloticus, Litopenaeus vannamei, Ictalurus punctatus, Clarias gariepinus, Tachysurus fulvidraco, and Cyprinus carpio, However, only 40% of the reviewed studies addressed aspects related to the incorporation of RAS elements in their designs. In conclusion, the use of plants for wastewater treatment in CW systems is feasible; however, its application remains largely at the experimental scale. Evidence indicates that there are limited real-scale applications and few studies focused on the reuse of treated water for agricultural purposes. This highlights the need for future research aimed at production systems that integrate circular economy principles in this sector, through RAS–CW systems. Additionally, there is a wide variety of plant species that remain unexplored for these purposes. Full article

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