Aquaculture
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12348/2
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- This brief zooms in on the opportunities and challenges of seaweed farming in Timor-Leste. Initiated as a follow-up to the WorldFish organized National Seaweed Workshop in Dili in late June 2024, the brief also reports on our ongoing seaweed-related fieldwork, activities and research.
- Streptococcus agalactiae (Group B Streptococcus, GBS) poses a significant threat to Nile tilapia (Oreochromis niloticus) aquaculture, causing severe streptococcosis characterised by high mortality and economic losses. This study elucidates the pathogenesis of S. agalactiae through an integrated diagnostic approach and evaluates bacteriophage therapy as a sustainable alternative to antibiotic treatments. Clinical signs in infected tilapia, including erratic swimming, exophthalmia, and haemorrhagic lesions, were accompanied by systemic postmortem findings such as hepatosplenomegaly and ascitic fluid accumulation. Comprehensive identification of S. agalactiae isolates from pond water and diseased fish was achieved using morphological, biochemical, serological, and molecular techniques, confirming its role as the causative agent. Concurrently, three bacteriophages (STRA1, STRA2, STRA3) were isolated from aquaculture ponds and characterised by their lytic efficacy, host specificity, and environmental stability. These phages exhibited tailed morphologies, high lytic activity (up to 83.3% against S. agalactiae), and resilience under pond-like conditions (pH 4.0–10.0, 28°C–50°C), with STRA1 demonstrating efficacy against multidrug-resistant strains. In vitro assays revealed significant bacterial load reductions (e.g., STRA3: 1.03 × 106 CFU/mL vs. control: 6.13 × 106 CFU/mL at 72 h), though resistant mutants emerged at low frequencies (8.11–8.40 × 10−4). Suboptimal water quality parameters, including low dissolved oxygen (3.6 mg/L) and elevated iron (1321 μg/L), likely exacerbated infection severity. These findings underscore S. agalactiae's pathogenicity and position bacteriophage therapy as a promising, eco-friendly biocontrol strategy, warranting further in vivo validation to optimise its application in tilapia aquaculture.
- The present study investigated the effect of dietary supplementation with ethanolic extracts of Ulva sp. and garlic (Allium sativum) on the growth performance, muscle composition, digestive enzyme activity and immune response of Pacific whiteleg shrimp (Litopenaeus vannamei). A60-day feeding trial was conducted using seven experimental diets, including a control and diets supplemented with varying concentrations of Ulva sp. extract (0.5, 1.0 and 2.0 g/kg) and garlic extract (2.0, 4.0 and 6.0 g/kg). Phytochemical analysis confirmed the presence of bioactive compounds such as flavonoids and phenolics in Ulva sp. and alkaloids, saponins and phenolic acids in garlic extract. Shrimp fed Ulva sp. extract showed significant improvements in crude protein content, essential amino acid composition and digestive enzyme activity, particularly protease and lipase activities, suggesting enhanced nutrient utilisation. Conversely, garlic extract supplementation resulted in increased fat content, indicating increased fat deposition, alongside a marked upregulation ofimmune-related genes, including Penaeidin3, Penaeidin4, HSP70 and proPO, highlighting its immunostimulatory potential. The combined findings suggest that Ulva sp. extract optimally enhances protein deposition and digestive efficiency, whereas garlic extract strengthens immune responses, making both promising functional feed additives for sustainable shrimp aquaculture. Future research should explore their synergistic effects and long-term benefits in commercial farming applications.
- The present research evaluated the value of adding 3, 5, and 7g of a probiotic mixture of Pediococcus acidilactici, Lactobacillus acidophilus, and Bacillus subtilis/kg fish feed on the physiological status and fish health of the Nile tilapia (Oreochromis niloticus). A total of 120 Nile tilapia fish were divided into four equal groups fed on pellets containing different ratios of the probiotic mixture for three months. After the experimental period, the whole body compositions (fats, protein, and ash content) of tilapia were affected significantly in all groups (P≤ 0.05). The immunological parameters, nitroblue tetrazolium (NBT) and lysozyme activities significantly increased in all treated groups. The results showed significant hematological parameters [Hematocrit (PCV), hemoglobin (Hb), erythrocyte counts (RBC), Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC)] and significant biochemical blood parameters [glucose, albumin, protein, globulin, aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] measured in serum after the experimental period. The number of Vibrio sp. isolated from the internal organs of experimental fish (muscles and liver) every month for three months was lower significantly in all treated groups than in the control. The relative level of protection (RLP) among the three treated groups after infection-challenge with Vibrio harveyi (0.1ml of culture suspension of pathogen containing 108 bacteria ml-1) was higher than in the control, and the highest record was in the fourth group. The present research results support the use of a mix of Pediococcus acidilactici, Lactobacillus acidophilus, and Bacillus subtilis at a rate of 7g/ kg standard fish diets supplementation as immunostimulants in common fish diets.
- Small indigenous fish species, such as mola carplet (Amblypharyngodon mola), play a crucial role in the diets of fish-dependent populations in India due to their rich micronutrient content. Recognized as a key species for promoting nutrition-sensitive aquaculture, mola has recently been successfully bred in hatcheries using standardized induced breeding and mass seed production protocols. This study assesses the economic viability of integrating mola seed production into an existing carp hatchery in Odisha, India. A comprehensive financial analysis, including cost-return assessment, bankability, economic performance, break-even analysis, and sensitivity testing, was conducted. The proposed model has a production capacity of 1 million seeds per cycle, with 24 cycles annually. The total investment required is INR 4,12,932 ($4,975), comprising capital expenses of INR 2,56,650 ($3,092) and annual operational costs of INR 1,56,282 ($1,883) considering loan component. The business model demonstrates strong profitability, with an operational profit margin of 53.57% at a selling price of INR 1,000 ($12) per 100,000 hatchlings. The break-even point is achieved at 17 production cycles per year and INR 885 ($10) of per unit of seeds price. Financial indicators confirm high viability, with a benefit-cost ratio of 1.67, a net present value of INR 2,28,233 ($2,750), and an internal rate of return of 32.94%. The model is also bankable, evidenced by a debt service coverage ratio of 1.63, and remains profitable under various sensitivity scenarios. These findings highlight the potential for integrating mola seed production into existing carp hatcheries, offering a scalable and sustainable approach to strengthening small indigenous fish farming and advancing nutrition-sensitive aquaculture in India.
- To contextualize IMTA in Kenya, on February 17th to 24th 2025 WorldFish, organized for a scoping study to define IMTA. The activity was conducted by engaging participants in a 2-day training, further, the team also conducted field data collection across the five coastal counties. The activity was implemented under Work Package 2 of the Asia-Africa Bluetech Superhighway (AABS) project. IMTA is one of the four work packages that AABS is supposed to implement over seven years of the project to improve the livelihoods of vulnerable coastal communities and to restore marine and coastal ecosystems in countries across Africa and Asia. IMTA is a system in which waste materials from one species serve as food for the next, creating a loop of healthy and sustainable aquaculture through bio-mitigation.
- The Asia–Africa BlueTech Superhighway Technical Evaluation and Interim Recommendation Report provides a comprehensive assessment of various climate-smart technologies aimed at reducing aquatic food loss and waste in East African fisheries. Authored by Christoph Müller, Heike Hoedt, and Aditya Parmar, the report focuses on solar-powered solutions for drying, cooling, cooking, and ice production, all designed to enhance sustainability, reduce operational costs, and improve fish preservation.
- This report summarizes the field visits conducted in Mozambique from 5th To 17th March 2025 , by the Worldfish (WF) contracted consultant from Simply Solar GbR and the local Worldfish Research Associates, supported by the IDEPA headquarter and local delegations as well as the local WCS delegations. The team consisted of Helena Salência from Worldfish and Christoph Müller from Simply Solar GbR. The purpose of the field visits was to gather insights into the fisheries activities around Maputo Bay, including Ilha de Inhaca and in the Nampula region. In the Nampula region, Carlos Meirinhos from the local WCS office supported the team.
- In August 2024 Simply Solar conducted an assessment visit to stakeholders and installations in coastal fisheries in Kenya. Aim was the identification and review of existing technologies in the fish industry: for processing (thermal processing) and cooling at the project locations. This review shall help understand what is already available at the project's sites and the technological gaps that can be quickly filled with existing options. Based on the learning from the assessment visit to Kenya and based on the information and orientation given by Worldfish consultant Yahya Mgawe and representatives of Tanzanian project partners the assessment visit concentrated on private stakeholders and Cooperatives, rather then BMUs.
- In June 2024 Simply Solar conducted an assessment visit to stakeholders and installations in coastal fisheries in Kenya. Aim was the identification and review of existing technologies in the fish industry: for processing (thermal processing) and cooling at the project locations. This review shall help understand what is already available at the project's sites and the technological gaps that can be quickly filled with existing options.
- This user manual is produced as a part of center for renewable energy in aquaculture (CeREA), a 4-year groundbreaking intiative funded by the Royal Norwegian Embassy in Cairo. Its offers information and guidance to fish farms regarding the effectiveness and sustainability of on-grid solar energy systems, which are integral for supporting operational processes, such as water and aeration pumps, thereby leading to a reduction in operational costs.
- This manual is produced as a part of center for renewable energy in aquaculture (CeREA), a 4-year groundbreaking intiative funded by the Royal Norwegian Embassy in Cairo. It provides practical guidance to ensure fish quality and enhance economic value. It also serves as a comprehensive step-by-step resource for handling fish from production to end-users. It includes essential information on preservation, handling, processing and value addition of fresh fish, along with general guidelines on effective cooling techniques
- This user manual is produced as a part of center for renewable energy in aquaculture (CeREA), a 4-year groundbreaking intiative funded by the Royal Norwegian Embassy in Cairo. It provides guidance on opertion and mainatance of solar-powered-coolers designed to keep fish fresh for extended periods without relying on the electricity grid using solar energy. The model is ideal for rural areas and markets distant from electrical infrastructure. The manual includes detailed explanations of the cooler’s components, along with instructions for installation, operation, and maintenance to ensure optimal performance.
- This user manual is produced as a part of center for renewable energy in aquaculture (CeREA), a 4-year groundbreaking intiative funded by the Royal Norwegian Embassy in Cairo. It offers information for off-grid solar-powered water pumping system in remote areas where the local electricity grid is inaccessible. The system relies on photovoltaic cells that generate electricity during the day, primarily to operate water irrigation that are essential for maintaining stored energy, which can be used to power various equipment on the farm, particularly aeration systems.
- This user manual is produced as a part of center for renewable energy in aquaculture (CeREA), a 4-year groundbreaking intiative funded by the Royal Norwegian Embassy in Cairo. It provides guidance on using biogas system in fish farms as a sustainable source of renewable energy, aimed at reducing operational costs while enhancing the surrounding environment. The manual details how to transform organic waste into useful energy, which contributes to improved performance in aquaculture and increased productivity. By implementing these practices, fish farms can achieve greater sustainability and operational efficiency.
- Aeromonas veronii biotype sobria is a potential aquatic zoonotic pathogen and a major cause of freshwater bacterial infections in cultured fish globally, leading to substantial economic losses. This study aimed to establish the median lethal dose (LD50-96 h) for Aeromonas veronii biovar sobria A4 strain and to demonstrate induction of clinical signs, gross and microscopic lesions in experimentally infected juvenile Nile tilapia (Oreochromis niloticus). Aeromonas veronii biotype sobria A4 strain used in this study were obtained from water samples from ponds with high fish mortality at Cavarino farm in Narok County, Kenya. Six groups each comprising 10 fish were intraperitoneally injected with 0.1 mL of A. veronii biovar sobria A4 strain suspension at: 1.5 × 104, 1.5 × 105, 1.5 × 106, 1.5 × 107, 1.5 × 108, and 1.5 × 109 colony forming units per mL (CFU/mL) respectively and the bacteria was afterward recovered from kidney and hepatopancreas of freshly dead fish. Duplicate control groups (each n = 10) were injected with sterile physiological saline before the lethal dose group were injected with varying concentration of the A. veronii biovar sobria A4 strain. The LD50-96 h of A. veronii biovar sobria A4 strain was found to be 1.5 × 108 CFU/mL. Clinical signs and gross lesions observed in the lethal dose group were: skin hemorrhages (20%), erosion of the fins including caudal fin with scale loss exposing underlying skin (13.7%), congested and hemorrhagic gills (15%), hepatic hemorrhages and enlargement (21.3%), distension of gall bladder (18.8%), splenomegaly and congestion (22.5%), and ascites (16.3%). The main histopathological lesions observed in the gills were focal hemorrhages, atrophy of the filaments and loss of lamellae in some filaments with mononuclear cellular infiltration; on the liver there were; hemorrhages, infiltration with lymphocytes and melanomacrophages, degenerative hepatocytes and focal necrosis. There was extensive hemosiderosis with increased melanomacrophages in the spleen. The kidney showed extensive hemorrhages, localized coagulative necrosis, atrophied glomeruli and multifocal mononuclear cellular infiltration in the interstitium. The findings will lay a foundational basis for subsequent investigations into the host-pathogen interaction, therapeutic approaches, and epidemiology of Aeromonas veronii biovar sobria.
- Parasitic infections threaten the endangered Oreochromis jipe and other ichthyic populations in Lake Jipe, thereby hindering conservation efforts. Initiatives have been made to farm O. jipe as a conservation strategy. To develop effective conservation approaches and ensure the species' survival in its natural habitat and aquaculture systems, it is imperative to understand the diverse parasites in these habitats. Consequently, this cross-sectional study was conducted to determine parasitic loads in tilapias from selected farms and Lake Jipe. A total of 111 fishes were collected (76 farmed, 35 from the lake), comprising 66 O. jipe, 34 Oreochromis niloticus and 11 hybrids of O. jipe and O. niloticus. The fish were euthanized, necropsied and examined for parasitic infections via visual inspection and light microscopy. Out of 111 fishes examined, 58 (52.3%) were infected with 212 parasites, including 135 (63.7%) and 77 (36.3%) from farm and lake habitats, respectively. The prevalence of parasitic infections in fish from the lake and farm habitats was 68.6% and 44.7%, respectively. The most frequently occurring parasite genera identified were Diplostomum (30.63%), Acanthocephalus (20.7%), Dactylogyrus (9.9%) and Contracaecum (2.7%), with mean intensities of 2.9, 3.7, 1.9 and 1.7, respectively. Contracaecum and Camallanus were exclusively found in fish from Lake Jipe, while Euclinostomum and Gyrodactylus were only observed in farmed fish. O. jipe had the highest prevalence of parasitic infections (59.1%), followed by O. niloticus (44.1%) and hybrids (36.4%) (p > 0.05). In conclusion, the examined fishes were infected with diverse parasites, which have both public health concerns (Euclinostomum and Acanthocephalus) and economic significance (Dactylogyrus and Gyrodactylus). Consequently, it is imperative to enhance public awareness and enforce biosecurity measures to mitigate potential health risks and to improve the productivity of the pond culture system and lake ecosystem. These measures will help reduce parasite dissemination and promote sustainable fish production and populations.
- Aquaculture plays a vital role in enhancing food security in Africa but faces challenges in the fed aquaculture sector, particularly in accessing and producing high-quality aquafeeds. To address this, FAO organized the “Expert Workshop on Local Alternative Ingredients, Aquafeed Supply, and Feeding Management” in Egypt in 2023. Experts and stakeholders from nine African countries—Cameroon, Egypt, Ghana, Kenya, Malawi, Nigeria, Uganda, the United Republic of Tanzania and Zambia—participated, alongside representatives from governments, academia, development agencies, the private sector, and farming communities. Pre-workshop questionnaires informed national reports on feed ingredient supply, feed manufacturing, and feeding management practices. These reports, along with workshop discussions, form the basis of this technical document comprising nine country analyses and a regional synthesis. Common challenges identified include limited access to alternative feed ingredients, poor feed preparation and storage practices, inadequate monitoring of on-farm feeding, lack of investment for small-scale producers, low technical capacity among farmers, poor feed quality, and weak regulatory frameworks. The synthesis report recommends key actions: stabilizing feed ingredient supply and costs, promoting training for feed producers and farmers, improving on-farm feed and water quality management, enhancing data collection and analysis, expanding access to finance and storage facilities, and strengthening collaboration among stakeholders. These measures aim to build a more efficient, sustainable, and resilient aquaculture sector across the region.
- The Clostridium autoethanogenum-derived protein (CAP) is a microbial protein generated during ethanol fermentation of agricultural byproducts. The present investigation evaluated the use of CAP as a sustainable alternative to reduce fishmeal (FM) dependency in aqua-feeds. A 70-day feeding trial was done to examine the impacts of partially replacing FM protein by CAP at 0 % (control, CAP0), 10 % (CAP10), 20 % (CAP20), 30 % (CAP30), and 50 % (CAP50) inclusion levels in diets for European seabass (Dicentrarchus labrax) juvenile (initial weight 10.5 ± 1.5 g). Results obtained demonstrated that dietary CAP incorporation up to 50 % FM replacement did not significantly (P > 0.05) impact the growth performance, feed efficiency, or survival rates. Similarly, the expression levels of growth-related genes (IGF-1 and GH) remained unchanged across treatments. The intestinal digestive enzymes activities, including lipase, alpha-amylase, and proteases, as well as the haematological parameters remained unaffected by the dietary CAP inclusion levels. Histological assessment revealed normal tissue architecture in the intestine, liver, and spleen of fish fed on CAP-containing diets. That indicats no adverse effects of CAP on organs’ structure. A simple economic analysis showed reduced feed costs with increasing CAP inclusion, where production costs per ton of fish gain decreases by 19.3 % at 50 % FM replacement compared to the control diet. These findings establish that CAP is a viable and cost-effective protein source capable of replacing up to 50 % FM protein in practical diets for D. labrax juveniles without compromising their growth, health status, or organs’ structure.
- The Apatani community in Arunachal Pradesh, India has long practiced rice-fish coculture, integrating rice cultivation with fish farming to enhance food security and promote environmental sustainability. This traditional method utilizes the region’s wet rice terraces, allowing for the simultaneous production of rice and fish, contributing to efficient land and water resource utilization. Despite the organic nature of this practice, challenges such as suboptimal input distribution, inappropriate combinations of rice and fish species, and limited access to training have hindered productivity. The overall average yields of 1389 kg/ha for rice and 209 kg/ha for fish, indicating room for improvement. This study focused on optimizing resource utilization and fund allocation among Apatani farmers in Ziro Valley to address these issues. Data were collected from a random sample of 200 farmers across the valley. Using Cobb-Douglas production functions, researchers estimated rice and fish yields through regression models. Subsequently, a non-linear constrained optimization problem based on the Nash-bargaining framework was solved to assess the effects of optimization on fund allocation for various inputs. The findings revealed that rice and fish yields could potentially exceed 2000 kg/ha and 300 kg/ha, respectively, with proper resource management. Critical factors identified for enhancing productivity included using mixed manure and stocking fingerlings. Moreover, improving farmers’ technical knowledge and skills through institutional support and policy interventions was deemed vital for establishing rice-fish coculture as a sustainable livelihood in Ziro Valley. In conclusion, while the Apatani community’s traditional rice-fish coculture system offers a foundation for sustainable agriculture, targeted optimization of resource utilization, combined with enhanced training and institutional support, is essential to realize its full potential in improving productivity and ensuring long-term sustainability.