Search Results (88)

Effective surveillance of viral disease in fish populations is critical for disease control and the sustainable development of global aquaculture. Here, we evaluated the application and performance of pooled serum samples using an indirect ELISA based on recombinant segment 4 protein to assess farm-level immunity in tilapia infected with Tilapia lake virus (TiLV). The TiLV-S4 ELISA was developed using a recombinant nucleoprotein (segment 4) antigen, optimized through checkerboard titration, and validated for repeatability and reproducibility, with intra- and inter-assay coefficients of variation below 10%. A pooling strategy was used to combine multiple serum samples before testing for the presence of TiLV-specific antibodies using an enzyme-linked immunosorbent assay (ELISA). Our results showed that pooling five serum samples was effective for detecting TiLV-specific antibodies, particularly when multiple seropositive individuals were presented in the pool, supporting its application for population-level surveillance. However, ELISA sensitivity may be reduced when only one seropositive sample is included in the pool, due to the dilution effects. Despite this limitation, pooled testing yielded a high proportion of positive results, suggesting similar detection performance in many cases. Overall, the pooling strategy provides a cost-effective and time-efficient approach for large-scale monitoring of immune status in tilapia populations. Full article

Sulfamethoxazole (SMZ), a widely used broad-spectrum antibiotic in aquaculture, lacks comprehensive research on its residual elimination kinetics in tilapia. This study investigated SMZ residue depletion, withdrawal periods, and dietary risks in 1-year-old GIFT tilapia (Genetically Improved Farmed Tilapia Oreochromis niloticus) weighing 500 ± 50 g, following oral gavage administration of a loading dose (200 mg/kg BW on day 1) and then 100 mg/kg BW daily for 6 more days, at 22 ± 2 °C. Tissue samples (plasma, muscle, skin, liver, kidney, gill, and remaining tissues) were collected from five fish per time point at intervals from 0.33 to 30 days post-administration, with SMZ residues quantified via HPLC-MS/MS. Results revealed peak SMZ concentrations at 0.33 days (8 h), ordered as liver > skin > plasma > kidney > remaining tissues > gill > muscle. Muscle residues fell below the maximum residue limit (MRL, 100 μg/kg) by day 3, while skin required 10 days. Kidney residues dropped below the limit of detection (LOD) earliest (16 days), followed by muscle, gill, and remaining tissues (25 days), whereas plasma, liver, and skin retained detectable levels until day 30. Elimination equations for SMZ across tissues exhibited first-order kinetics. Based on the specific conditions of this study, a minimum 11-day withdrawal period is recommended for edible tissues (muscle + skin) after SMZ administration. Hazard quotient (HQ) values for all tissues remained below the safety threshold (HQ = 1), indicating low dietary risk. These findings support SMZ use standardization in tilapia aquaculture to ensure food safety compliance. Full article

The cage tilapia farming boom in Kenya’s Lake Victoria region underscores its role in food security and economic growth. Success depends on understanding producer and consumer behaviors within the value chain. Using the Theory of Planned Behavior (TPB), this study examines how attitudes (evaluations of farming/consumption), subjective norms (social pressures), perceived behavioral control (confidence in actions), environmental awareness, and moral obligation shape decisions. A survey of 66 producers and 169 consumers, analyzed via structural equation modeling (SEM), reveals key drivers. Producers are driven by positive attitudes toward profitability, technical feasibility, and sustainability, reinforced by community norms and resource access, promoting sustainable practices. Consumers prioritize health, affordability, and accessibility of cage-farmed tilapia, with environmental and ethical factors less influential. These findings highlight opportunities for targeted interventions to enhance production, boost demand, and ensure sustainable aquaculture. Full article

Effective sustainable fish farming necessitates enhanced models that incorporate environmental variability and contemporary monitoring methods. This research presents an innovative framework for assessing and modeling the environmental carrying capacity based on phosphorus (ECCp) in tropical and neotropical lakes and reservoirs. The model evaluates phosphorus waste from tilapia farming (Oreochromis niloticus) under diverse climatic conditions and production scenarios in cage systems. Using bioenergetic modeling and Monte Carlo simulations, we estimated phosphorus retention in fish and maximum production limits across different temperatures (21 °C, 25 °C, 29 °C) and dietary phosphorus concentrations (0.8%, 1.2%, 2.1%) in Brazil’s Chavantes reservoir. Results indicated that phosphorus retention diminished with higher dietary phosphorus and increased temperatures, ranging from 51% (0.8% P) to 20% (2.1% P). Phosphorus discharge ranged from 3.3 to 20.5 kg/ton of fish produced. The ECCp model forecasted an allowable production of roughly 40 tons per year at full operational capacity, reflecting a 41% increase compared to current regulations. The model’s accuracy (96%) surpassed that of traditional regulatory frameworks, which rely on static parameters, emphasizing the shortcomings of existing practices. The findings promote enhanced modeling strategies, sophisticated monitoring, adaptive management, and revised public policies to mitigate phosphorus emissions and support sustainable aquaculture in tropical and neotropical regions. Full article

Nile tilapia (Oreochromis niloticus) is the most widely farmed tilapia species globally, making it one of the most important aquaculture species. To meet increasing demand, hatcheries occasionally use artificial breeding techniques such as hormonal induction to synchronize breeding. Despite the common use of human chorionic gonadotropin (hCG) in fish breeding, no detailed protocol has been established specifically for Nile tilapia. The objective of this study is to establish an effective hCG-induced artificial breeding protocol for gene editing and aquaculture production, optimizing fertilization, hatching, and survival rates. We employed a single intramuscular injection of 2 IU/g hCG to induce ovulation. The protocol achieved an average fertilization rate of 88.3% and a larval survival rate of 90.5%, demonstrating its potential for obtaining high-quality embryos for functional studies and enhancing reproductive performance on a commercial scale. Full article

This study highlights the significant environmental and health risks associated with heavy metal contamination (As, Cd, Cr, and Pb) in Oreochromis niloticus (Nile tilapia) from two locations: the Khon Kaen municipal landfill (study site) and the Thapra commercial fish farm (reference site). It also evaluates potential human health risks and investigates genotoxicity and oxidative stress markers, including malondialdehyde, hydrogen peroxide (H₂O₂), catalase (CAT), and superoxide dismutase (SOD) in fish. Heavy metal concentrations were analyzed using inductively coupled plasma optical emission spectrometry. To determine genetic differentiation, inter-simple sequence repeats with dendrogram construction and genomic template stability (%GTS) were applied. The results showed that the average concentrations of As, Cd, Cr, and Pb in water samples were 0.0848, 0.536, 1.23, and 0.73 mg/L, respectively. These values exceeded safety limits, and the average Cd in sediment (1.162 mg/kg) was above regulatory thresholds. In fish muscle, the average metal concentrations (mg/kg) followed the order Cr (1.83) > Pb (0.69) > Cd (0.096) > As (0.0758), with Pb exceeding food quality standards. The bioaccumulation factor ranked as Cr > Pb > As > Cd. Health risk assessments, including health risk index and carcinogenic risk, suggested Pb contamination poses significant health risks through fish consumption. From dendrogram results, the %GTS of O. niloticus from the landfill and reference sites were 46.34 to 71.67% and 87.34 to 96.00%, respectively. This suggests that fish from the landfill site exhibited greater genetic diversity compared to those from the reference site. Specific oxidative stress markers revealed higher levels of H₂O₂ and significantly lower activities of CAT and SOD in landfill O. niloticus than in the reference site. These results emphasize the urgent need for environmental monitoring, stricter pollution controls, and improved waste management strategies to protect aquatic ecosystems and human health. Full article

The tilapia (Oreochromis) aquaculture industry in Malaysia has expanded rapidly to meet the increasing demand for animal protein. However, this growth is challenged by microbial infections, particularly those caused by the emerging pathogen Aeromonas dhakensis. This study aimed to investigate the microbial community composition across four distinct tilapia farming systems and assess associated water physicochemical parameters, with a focus on detecting the presence of A. dhakensis and elucidating its environmental associations. Water physicochemical parameters were measured to evaluate environmental conditions, microbial communities were characterized through 16S rDNA metabarcoding, and A. dhakensis was detected using both microbiological and molecular approaches. Principal component analysis (PCA) and canonical correspondence analysis (CCA) were employed to explore the influence of environmental variables and microbial community dynamics on pathogen occurrence. Our results indicated that floating cages exhibited higher levels of temperature, ammonium, and fecal coliform, while cement tanks showed signs of nutrient accumulation. PCA revealed that both systems were associated with degraded water quality. A total of 45 A. dhakensis strains with distinct fingerprints were isolated. The 16S metabarcoding revealed Proteobacteria, Actinobacteria, and Planctomycetota as the dominant phyla. Alpha diversity did not differ significantly among pond systems, while beta diversity revealed variations in microbial assemblages across aquaculture systems. CCA identified dissolved oxygen, temperature, macronutrients (phosphate, ammonium, nitrate, and nitrite), and turbidity as significant environmental drivers shaping the microbial community structure across the pond systems. In conclusion, this study highlights the importance of environmental factors, particularly dissolved oxygen, temperature, and nutrient levels, in shaping microbial community composition and potentially influencing the presence of pathogenic bacteria such as A. dhakensis. These findings underscore the need for improved environmental management in tilapia aquaculture to mitigate disease risks and support fish health. Full article

Clinostomum is a genus of parasitic trematodes found worldwide, infecting a wide range of hosts, including freshwater fishes, snails, birds and occasionally humans. In this study, clinostomid metacercariae were collected from Nile tilapia raised in fish farms in the Upper Tana River region, Kenya. The prevalence of infection was 17.2%, with metacercariae infecting the skin, gills and buccal cavity of the fish. Using light microscopy, scanning electron microscopy (SEM) and molecular methods targeting both nuclear ribosomal (ITS1, 5.8S, ITS2) and mitochondrial (COI) regions, the metacercariae were identified as C. cutaneum, C. phalacrocoracis, C. tilapiae and Euclinostomum heterostomum. The three species of Clinostomum have previously been reported to infect fish or piscivorous birds in Kenya, while this is the first report of E. heterostomum in this country. SEM analysis revealed new ultrastructural features of C. cutaneum, including an excretory pore surrounded by minute spiny papillae, an everted cirrus and dome-shaped papillae on the tegumental area around the genital pore. The cirrus lacked basal papillae, showing morphological variation between the adult and metacercarial stages. Our study, therefore, provides new insights into the phenotypic identification of flukes that may be pathogenic to fishes and humans and, therefore, of scientific and practical importance. Full article

This study evaluates the efficacy of a new florfenicol-based drug, both in vitro and in vivo, in Nile tilapia (Oreochromis niloticus) against pathogens commonly found in fish farming and its withdrawal period. The drug’s efficacy was tested using prophylactic, metaphylactic, and therapeutic approaches against Streptococcus agalactiae (serotypes Ib and III) and Francisella orientalis. The minimum inhibitory concentration of florfenicol was 4, 5, and 128 μg/mL for the different pathogens. Fish mortality was lower in the prophylactic treatment compared to the metaphylactic and therapeutic treatments for S. agalactiae. No difference in mortality was observed for F. orientalis across treatments. Mild to moderate lesions suggestive of intoxication were observed, mainly in the liver of fish treated with overdoses or exposed to low temperatures. Florfenicol reduced mortality rates, especially with early treatment (metaphylactic), in fish experimentally challenged with the pathogens. Moreover, prophylactic antimicrobial use is not recommended, as it promotes the selection of multidrug-resistant bacterial strains. Additionally, the residual concentration of the drug in muscle tissue lasted for a shorter period than that recommended by the manufacturer, and at lower concentrations than required by national and international legislation. Full article

Despite the importance of Nile tilapia as a main aquaculture species in Uganda, limited research has been conducted concerning its genetic diversity, particularly in farmed populations. This gap has hindered the development of a systematic breeding program for this species. Successful aquaculture development, especially for genetic improvement, relies on the diversity and purity of wild and farmed populations as germplasm sources for selective breeding. Using microsatellite markers, the current study evaluated the genetic diversity of 480 samples collected from 20 populations of Nile tilapia (Oreochromis niloticus) in Uganda. All the populations exhibited a higher expected heterozygosity (0.50 ± 0.01) than observed heterozygosity (0.42 ± 0.01), although this was not significantly different. Populations from ponds showed lower FST values (<0.001), an indication of lower genetic differentiation. The populations formed four main clusters; the first comprising of mainly cages (Pal and Busana), the second with cages: Katosi and SON in addition to Rocks hatchery, the third comprised of Bawe cage fish farm and Tendo hatchery, and the fourth were populations from ponds and beaches on Lake Victoria. Given the higher genetic diversity and genetic differentiation of Tendo and Rocks populations, these farms would provide potential candidates for the development of local strains in Uganda. These results provide more insights into the management of local Nile tilapia strains towards reduction of inbreeding levels. Full article

The study investigates the economic aspects of red tilapia (Oreochromis sp.) production using biofloc technology under different electrical energy sources. Conducted at the El Vergel Fish Farming Association in Arauca, Colombia, the study examines four energy treatments: conventional energy (CE), combined conventional and photovoltaic energy (CPVE), full photovoltaic energy (PVE), and simulation of photovoltaic energy generating surplus for nighttime use (PVES). The water quality and zootechnical performance met the species requirements, with dissolved oxygen decreasing as fish size increased. The PVE treatment had the highest initial investment due to solar panels and battery costs, but it also had the lowest operating energy costs. However, the overall costs of the PVE treatment increased due to depreciation and maintenance. Feed was the largest production cost, followed by labor in most treatments, while depreciation was a major cost for the PVE treatment. The total operating cost (TOC) of the photovoltaic energy systems (PVE and PVES) was lower compared to that of conventional energy (CE), with PVES showing the highest cost savings. The reduction in energy costs highlights the potential for solar energy systems to enhance the economic viability of aquaculture production, making these systems a favorable option for sustainable production in the long term. Full article

Streptococcus agalactiae is an important pathogen responsible for cases of high mortality in farmed and wild fish worldwide. In Brazil, this bacterium has been commonly associated with outbreaks in Nile tilapia farms, but other native fish species are also susceptible. Since floating cages are one of the most common culture systems used in the country, the close contact between farmed tilapia and native fish species presents a risk concerning the transmission of this pathogen. In this study, we characterized a mortality outbreak in free-living trahira and in farmed arapaima, as well as the genetic and antimicrobial susceptibility patterns of the isolates obtained. During the outbreaks, moribund fish were sampled and subjected to bacterial examination, after which the isolates were identified via MALDI-ToF analysis. Genotyping was evaluated using repetitive sequence-based PCR (REP-PCR) and multilocus sequence typing (MLST). Antimicrobial susceptibility was evaluated using disc diffusion assays. In addition, whole-genome analysis also was performed. S. agalactiae was identified in all diseased fish, all of which belonged to serotype Ib; however, trahira strains were classified as non-typeable lineages in the MLST assay, while arapaima strains were classified as ST260. These isolates were shown to be similar to the main genotype found in Nile tilapia in Brazil, using REP-PCR, MLST and phylogenomic analysis. The pathogenicity of the bacterium was confirmed by Koch’s postulates for both fish species. The antimicrobial susceptibility assay showed variable results to the same antibiotics among the isolates, prompting four of the isolates to be classified as multidrug-resistant. This study represents the first report of a natural outbreak of Streptococcus agalactiae infection in wild trahira and farmed arapaima inhabiting the same aquatic environment as Nile tilapia. Full article

Brasília, Distrito Federal, is among the Brazilian cities with the highest number of tilapia farms, with around 660 farms, of which 112 are commercial. The aim of this study was to validate a health characterization model for commercial tilapia production using the production chain in the Distrito Federal (DF), one of Brazil’s 27 federative units, by applying a semi-structured questionnaire. A total of 112 farms were categorized according to the degree of vulnerability to the introduction of pathogens and the risk of dissemination using two weighted scorecard tables that evaluated 15 items each. After calculating the mean between the two variables, the farms were classified from A (insignificant risk) to D (high risk). Most of the commercial tilapia farms in the Distrito Federal were categorized as B (39; 34.8%) and C (53; 47.3%), representing low and medium risk, respectively. When comparing the different commercial groups, a significant difference (p < 0.05) was observed in the mean scores between closed-system fattening farms and both semi-closed fattening farms and pay-to-fish farms. Closed-system fattening farms, such as those using biofloc, aquaponics, and recirculation aquaculture systems, showed the lowest vulnerability to pathogen entry and the lowest risk of disease spread. The study’s findings provide valuable health information for the official veterinary service of the DF, enabling the categorization of farms, identification of production units, and determination of the most vulnerable strata. Furthermore, the model can be easily applied by private companies and by official veterinary services in other states or countries with significant tilapia production that need to implement risk-based surveillance programs for tilapia farms. Full article

The rapid growth of shrimp farming, particularly of Penaeus vannamei, accounts for about 80% of the global production of farmed shrimp and involves the cultivation of approximately 383 to 977 billion individuals annually, which highlights the urgent need to address the ethical and technical implications of raising potentially sentient beings. This study builds on the state-of-the-art assessment of sentience, consciousness, stress, distress, nociception, pain perception, and welfare to adapt the General Welfare Index (GWI) for farmed shrimp. The GWI is a quantitative index developed by our research group to measure the degree of welfare in aquaculture, and it has been previously applied to grass carp and tilapia. Using the PRISMA methodology and the creation of a hypothetical shrimp farm, the GWI, with 31 specific and measurable indicators across various welfare domains, is adapted to P. vannamei, offering a comprehensive assessment framework. The inclusion of quantitative welfare indicators promises to improve living conditions in alignment with legislation adopted on decapods’ sentience and contemporary scientific advances. Full article

Tilapia (Oreochromis niloticus), which is extensively farmed globally and ranks as the second most cultivated fish in the Philippines, generates significant amounts of waste that are often underutilized. One specific type of waste material consists of fish heads, which contain a valuable source of extracellular matrix (ECM). This study aims to evaluate the effects of sonication as a viable decellularization method for the extraction of ECM from tilapia fish heads. Particularly, two treatments were tested on the head samples: sonication-assisted decellularization (dWS) using a water bath sonicator, and decellularization without sonication (dNS), each with different contact times (5 min and 10 min). Histological analysis with H and E staining and DNA quantification revealed that sonication-assisted samples (dWS) showed a greater reduction in basophilic components and DNA content, achieving a 93.7% removal rate. These dWS samples also had the highest protein loss, retaining only 33.86% of the original protein. SDS–PAGE analysis indicated that both dWS and dNS samples maintained similar collagen structures, as evidenced by identical subunit bands. ATR–FTIR spectra confirmed the presence of collagen type I in all samples, detecting characteristic amides A, B, I, II, and III. The results revealed that varying treatments and contact times had significant effects on the physical and mechanical properties of the decellularized extracellular matrix (ECM). These findings highlight the effectiveness of sonication in the decellularization process, particularly for utilizing waste tilapia heads. Full article