The blue transformation roadmap promotes inclusive, sustainable, and resilient food systems, with integrated aquaculture agriculture (IAA) driving this shift by improving resource efficiency, recycling nutrients, diversifying incomes, and strengthening farm profitability and resilience. Despite the growing adoption of IAA systems in Africa, the impact of system inefficiencies on productivity remains poorly understood in some countries, including Malawi. Therefore, this study analyzed the technical efficiency of IAA farmers in Mchinji, using a translog stochastic frontier approach. Data from 105 IAA farmers, collected between August and September 2022, revealed that fish-crop integration was a predominant technique (73.7%) primarily utilizing vegetables and maize, an indication of prevalent low-input IAA systems. Increasing feed and fertilizer quantities, farm size, and the number of fish stocked could enhance efficiency, while labor had no significant effect. The average technical efficiency was 51%, indicating that it is possible for farmers to increase the level of output by about 49%. Furthermore, access to credit and extension services was identified to reduce inefficiencies. Therefore, strengthening institutional support is critical to improve productivity and sustainable fish farming practices.
Aquaponics offers a promising solution to meet growing food demand. We evaluated the feasibility of producing nursery-sized Nile tilapia and tatsoi using a hybrid recirculating aquaculture system (RAS)-biofloc approach to assess the biological, technical, and financial aspects. The study followed five key steps: system installation, cultivation, biological, and water quality assessments, technical analysis, and financial evaluation. Results showed favorable growth, with Nile tilapia reaching 63.92 g/individual (SGR: 1.32%/day; FCR: 1.83) and tatsoi yielding 70.26 g/plant over 28 days. Water quality parameters such as pH (6.9 to 7.8), temperature (23.2 degrees C to 26.4 degrees C), and dissolved oxygen (3.6 to 4.5 mg/L), was within optimal ranges. Technical reliability was demonstrated by stable system operation. Financially, the benefit-cost ratio ranged from 1.55 to 1.80, and the internal rate of return reached 33% to 37%, indicating profitability. Therefore, the hybrid RAS-biofloc system is biologically, technically, and financially feasible for industrial-scale cultivation.
The aim of this study was to evaluate the associated effect of mineral fertilization in the pond bottom soil and the use of commercial probiotic on the growth of Penaeus vannamei reared in a semi-intensive synbiotic system. The study was conducted in different commercial grow-out ponds testing two treatments: control (probiotic + synbiotic system) (18.40 +/- 4.98 shrimp m(-2). 0.004 g) and test (dolomite fertilization + probiotic + synbiotic system) (16.13 +/- 0.68 shrimp m(-2). 0.004 g). The control and test cycles lasted 94 and 98 days, respectively. The soil from the Test had a higher calcium, magnesium, phosphorus, sulfur, and organic matter (p < .05). The shrimp in the test had higher weight, survival, and yield (p < .05). Fertilizing the pond bottom with dolomite improved the soil mineral composition and, combined with probiotics in water and soil and synbiotic system, increased shrimp production rates in semi-intensive grow-out.
Hematologic and serum parameters are valuable indicators of fish health status. However, in rainbow trout (Oncorhynchus mykiss) aquaculture, limited information exists on how season and sex influence these parameters. This study evaluated the effects of season and sex on blood chemistry of rainbow trout broodstock across four seasons: summer (June-August), autumn (September-November), winter (December-February), and spring (March-May). Monthly sampling was conducted for one year on 296 healthy broodstock fish, and haemato-biochemical parameters were analyzed using standard methods. Red blood cell (RBC) and white blood cell (WBC) counts, hematocrit (Hct) and hemoglobin (Hb) peaked during summer and declined toward winter. Season and sex were significantly (& eng;p(2) > 0.8) linked to RBC count, Hb, and Hct, and their interaction significantly (& eng;p(2) > 0.8) affected WBC counts. Serum glucose (GLU), total protein (TP), cholesterol (CHOL), and triglycerides (TG) varied significantly (p < 0.05) across seasons, peaking in summer, while enzyme activities surged in autumn. Season exerted a strong effect on all biochemical parameters (& eng;p(2) > 0.8), whereas sex showed no significant effect, and their interaction influenced GLU, TP, CHOL, and TG levels. These seasonal and sex-specific baseline values improve hematology-based health monitoring and support informed broodstock management in rainbow trout aquaculture.
The ornamental fish industry faces financial challenges due to expensive ingredients. This study aimed to create cost-effective diets for juvenile guppy and swordtail using 15 local ingredients, reducing reliance on imports and lowering costs. Using linear programming, 18 feed formulations were developed, each with seven raw ingredients meeting nutritional needs. The feed costs varied significantly, with soybean-based diets being the most expensive, whereas, alternative protein sources such as Azolla pinnata (Az) and groundnut cake (GNC) emerged as the most economical substitutes. The inclusion of cassava flour (CF) significantly (p < .05) increased the expansion ratio (2.53 +/- 0.09) and water absorption index (4.53 +/- 0.10) of feed pellets. The Az diets resulted in pellets with lower bulk density (428.60 +/- 18.42 kgm(-3)) and higher floatability (86.67 +/- 5.77%hr(-1)). Alternative protein sources such as Az and GNC, along with the starch source CF, effectively reduced feed costs to less than $12 (USD) while maintaining physical and nutritional quality. Use of cost-effective ingredients (Az, GNC, and CF) not only lowers feed production costs but also satisfies the nutritional needs, thereby offering a sustainable solution for the ornamental fish industry globally.
This study investigated the factors that influence Bangladeshi consumers' purchase intention for freshwater prawn, with a focus on the mediating function of consumer attitude. Previous studies pay attention to the direct influencers (e.g. price, safety, and sustainability) of seafood consumption, with little emphasis on psychological mechanisms and quality attributes. To fill this gap, the study draws on consumer behavior theory and analyzes data collected from 386 interviews by using exploratory and confirmatory factor analyses alongside partial least squares structural equation modeling. The exploratory factors identified four key constructs, with freshness demonstrating the maximum factor loading (0.910), followed by size (0.868), consumption motivations (0.862), and past experience (0.822). The structural model confirmed that all the factors significantly increase purchase intention, both directly and through the mediating role of attitude. Among these factors, freshness had a stronger direct influence on attitude (beta = 0.241, t = 4.628, p < .001) and purchase intention (beta = 0.165, t = 3.252, p = .001) than other factors. Consumer attitudes, however, mediated these effects, amplifying the influence of product evaluations on purchase intention.
Polyculture farming of Nile tilapia and African catfish is widely practiced in Egypt, yet parasitic infections threaten production sustainability. This study compared Prohemistomum vivax encysted metacercariae (EMC) infections in both species using morphological, molecular, phylogenetic, physiological, and immunological analyses. A total of 500 fish (250 species) were collected seasonally from semi-intensive earthen ponds in Kafr El Sheikh Governorate. Clarias gariepinus showed higher overall prevalence (60.0% vs. 40.0%), peaking in summer (72.8% vs. 68.5%). However, Oreochromis niloticus exhibited significantly higher infection intensities (38.0 +/- 16.2 vs. 22.2 +/- 7.1 EMC/field in summer; p < .05). ITS sequencing confirmed P. vivax identity (99.71% similarity). EMC infections altered blood biochemistry, indicating liver dysfunction and elevated stress. O. niloticus demonstrated stronger immune responses, with TNF-alpha (10.0-fold muscle, 8.0-fold liver) and IL-1 beta (11.0-fold muscle, 9.0-fold liver) upregulation exceeding C. gariepinus (p < .05). These findings reveal species-specific susceptibility patterns, supporting seasonally adapted, host-specific parasite management strategies for sustainable aquaculture and zoonotic risk mitigation.
Aquaponic systems integrate fish cultivation with plant growth, creating a sustainable and resource-efficient method of food production. This study evaluated the growth performance, survival, and water quality of koi carp (Cyprinus carpio) and the growth of tomato (Solanum lycopersicum) and spinach (Spinacia oleracea) under different media bed conditions in an aquaponic system. The experiment was conducted for 60 days using cement tanks (three treatments in triplicate). Each tank contained 30 koi carp with an initial mean weight 98.75 +/- 0.24 g and an average length of 17.5 +/- 0.12 cm and was integrated with four plastic crates (44 & times; 32 & times; 14 cm) used as grow beds. Water quality parameters including pH, temperature, salinity, dissolved oxygen, hardness, alkalinity, ammonia, nitrite, and nitrate were monitored every five days and maintained within optimal ranges to support both fish and plant growth. Results indicated significant improvements in fish growth performance (p < .05), with a mean weight gain of 181.15 +/- 0.52 g, an average length increase of 13.0 +/- 0.26 cm, and a feed conversion ratio of 0.93. Effective biofiltration was achieved through balanced physicochemical parameters, which were supported by active nitrifying microbial activity and nutrient uptake by plants. Among the media tested, gravel beds supported superior plant growth compared to mixed or plastic media. Tomato plants showed significantly greater growth and biomass than spinach across all treatments. Overall, the study concluded that gravel-based aquaponic systems with different media beds promote faster and more efficient growth of koi carp, while offering a sustainable approach to integrated aquaculture and crop production that supports ecosystem-based food production strategies. Therefore, aquaponics shows strong potential as an efficient, sustainable, and scalable food production system.
The high cost of conventional culture media restricts large-scale cultivation of Ulva lactuca, highlighting the need for affordable nutrient alternatives. This study evaluated agricultural fertilizers, urea and diammonium phosphate (DAP), as nitrogen and phosphorus sources, respectively. Five treatments - urea (UE), DAP (DP), urea + DAP (UD), no urea (NU), and no phosphate (NP) - were tested under controlled laboratory conditions for 21 days with three replicates (n = 3). Growth, pigment content, gross primary productivity, and total antioxidant capacity were analyzed. Fresh weight increased 4.60, 2.97, and 4.06-fold in UE, DP, and UD treatments, respectively, compared to the control. UE and UD showed significantly higher gross primary productivity (p < .05). Regression analysis predicted a 13.85% biomass increase (R-2 = 0.79) under UD at 0.81:0.48 g L-1 (urea:DAP). These findings indicate that urea and DAP based formulations effectively enhance biomass and physiological performance under optimized conditions.
The present study evaluated the growth and survival of pearlspot, Etroplus suratensis, under two rearing environments, freshwater (0 ppt) and constituted saltwater (10 ppt), which differed in calcium and magnesium concentrations due to the addition of raw sea salt in the constituted saltwater. A 60-day experiment (initial weight: 29 +/- 2.5 g and stocking density: 20 fish/900 L) was conducted in duplicate in 1200-L fiber reinforcement tanks, each equipped with a biofilter. Water quality parameters and growth performance metrics of pearlspot were assessed in both treatments. Constituted saltwater exhibited substantially higher concentrations of calcium (38 mg/L), magnesium (285 mg/L) and total hardness (336 mg/L as CaCO3) compared to freshwater (calcium: 9 mg/L; magnesium: 42 mg/L; total hardness: 50 mg/L as CaCO3). Fish reared in constituted saltwater showed a significantly higher final mean weight (p < .05), daily weight gain (p < .01), percentage weight gain (p < .001) and condition factor (p < .001). Survival was also significantly higher (p < .05) in constituted saltwater, whereas mortality increased in freshwater, likely due to osmoregulatory stress. These findings highlight the importance of calcium and magnesium concentration in rearing water and support the use of raw sea salt to constitute saltwater at 10 ppt as a suitable medium for rearing E. suratensis in recirculatory aquaculture-based hatchery and nursery systems (RAS).
In many parts of the world, rural communities rely heavily on indigenous fish species to meet their nutritional needs, underscoring the need for sustainable farming practices. Diet optimization and effective environmental management are essential to promoting the health and well-being of these fish during domestication. In this study, we evaluated the survival and growth of Macrognathus pancalus, a high-value benthopelagic and overexploited food fish, using various food materials: live tubifex, zooplankton, a combination of zooplankton and tubifex, and an artificial feed as a control. Additionally, we assessed different floor substrates as habitats-sand, mud, a combination of sand and mud, and a control without any substrate. The experiments were conducted in triplicate in reinforced plastic tanks over a 90-day period. The results revealed that fish (0.60 +/- 0.08 g) fed with tubifex achieved significant growth of 1.89 +/- 0.22 g (p < .05) with the higher survival (81.33 +/- 2.31%), followed by those fed with a combination of mixed zooplankton and tubifex (1.38 +/- 0.12 g). It was observed that fish (2.40 +/- 0.75 g) in a water habitat without any substrate (control) achieved significant growth of 6.86 +/- 2.60 g (p < .05), followed by those in a sandy habitat (5.21 +/- 0.02 g). These findings suggest that feeding tubifex to fish in tanks without a floor substrate could be the most effective approach for the culture of this fish.
The dependence on fishmeal and fish oil in aquafeeds poses challenges to the long-term sustainability of aquaculture due to the pressure on limited marine resources. This study evaluated the potential of the microalga Haematococcus pluvialis (HP) as a partial substitute for fishmeal and a complete replacement for fish oil in the diet of black tiger shrimp (Penaeus monodon). Post-larvae (PL22) were reared for 56 days in a recirculating aquaculture system and fed five diets containing 0%, 8%, 12%, 16%, or 20% HP. Shrimp fed 12% HP showed significantly higher weight gain (1191.51%), daily weight gain (0.31 g day-1), and specific growth rate (4.56% day-1) compared with other dietary treatments (p < .05). Feed conversion ratio (1.09) and feed efficiency ratio (0.93) improved at 12% and 20% inclusion levels, respectively. Survival exceeded 95% at both levels, indicating that HP can effectively replace fish oil and partially replace fishmeal in shrimp feed.
This study examined the effects of a novel phytobiotic-based functional additive (Apex (R)) supplementation on the growth performance and disease resistance of the brown-marbled grouper. The experimental design consisted of three treatments: a control (0% additive), a medium-dose (0.3%), and a high-dose (0.7%) treatment, all applied over a 90-day period. Each treatment contained 75 fish with an initial weight of 8.3 g, replicated in three hapas. The results showed that supplementation with the additive significantly enhanced weight gain, specific growth rate, total length, and condition factor, as well as improved feed conversion ratio. Additionally, fish receiving dietary Apex (R) demonstrated reduced prevalence, intensity of ectoparasites, and Vibrio sp. loads, while showing increased levels of red and white blood cells, hematocrit, hemoglobin, lymphocytes, and monocytes. This study highlights the positive effects of novel phytobiotic additives on growth, immune response, and disease resistance in grouper aquaculture, supporting their potential application for sustainable fish farming.
Vibriosis, a bacterial disease, is considered a significant threat to the sustainability and economic viability of shrimp production. The present study evaluated the application of a predatory bacterium to control the population growth of pathogenic Vibrios in Pacific whiteleg shrimp (Penaeus vannamei). The predatory bacterium was identified as Bacteriovorax sp. OP175948.1 based on the 16S rRNA sequence. The Vibrio-inhibitory activity of Bacteriovorax sp. was evaluated using two independent trials with P. vannamei, exposed to two pathogenic Vibrios, including Vibrio parahaemolyticus and Vibrio harveyi. Each trial was conducted in five treatments, including a negative control, a positive control, and a treatment with Bacteriovorax sp. applied at 102, 104, and 106 plaque-forming units mL-1 (PFU mL-1). Results indicated that shrimp infected with V. parahaemolyticus and V. harveyi, and then treated with Bacteriovorax, showed a 6-fold increase in survival for V. parahaemolyticus and a 3-fold increase for V. harveyi, relative to the control. The shrimp treated with 104 to 106 Bacteriovorax sp. improved survival associated with a significant decline in Vibrio spp. counts in the shrimp tissues and rearing water. The Bacteriovorax sp. should be used as a practical strategy to prevent Vibrio-associated mortalities in P. vannamei aquaculture.
Technologies currently employed for land-based seaweed cultivation are cost-intensive and wasteful of resources. Hence, the present study examined natural and synthetic materials as growth substrates for a sustainable on-land production of Ulva spp. In total, 16 materials were qualitatively evaluated regarding their usability represented as availability, durability, reusability, and adherence, as well as growth of algae on the selected materials. The results of spore adhesion and mobility indicated that loofah sponge, clay pellets, and polyurethane foam were most suitable for algal adhesion. Synthetic materials generally exhibited low toxicity and high durability but low usability, as algal spores clogged the materials. In contrast, natural materials exhibited increased vulnerability to mechanical stress, leading to reduced durability and low reusability. Furthermore, toxic effects that might have inhibited movement and attachment of spores were more likely to occur from natural materials due to degradation processes during the tests.
This study evaluated the effects of artificial salinization strategies on the growth, water quality, and health status of Pacific white shrimp reared in a synbiotic nursery system. Four treatments were established: low-cost salt mixture with freshwater at salinity 3 g L-1 (LCSM), commercial salt mixture with freshwater at salinity 3 g L-1 (CS), seawater diluted to salinity 3 g L-1 (DS), and control; seawater at salinity 36 g L-1 (SW). Experimental units (60 L) were stocked with 2000 shrimp m-3 (12.0 +/- 1.0 mg). The LCSM, CS, DS, and SW resulted in a similar final weight (0.84 g, 0.84 g, 0.72 g, and 0.65 g, respectively). However, survival rates were lower in the LCSM treatment (70%) compared to the SW (90%). Our results demonstrated that despite low survival in the LCSM treatment, all low-salinity treatments provided good ionic profile, water quality, and shrimp growth.
Cryopreservation is an effective tool for the preservation of live biological materials. This study evaluated the suitability of cryoprotectant (CPA) impregnation protocols and the efficiency of ultrasound on Asian catfish (Clarias batrachus) embryos. Embryos at three developmental stages-morula, 6-somites, and tail elongation-were exposed to five CPAs (propylene glycol [PG], dimethylformamide [DFA], dimethyl sulfoxide [DMSO], methanol [MeOH], and ethylene glycol [EG] at concentration of 10%, 15%, 20%, and 25% for 20 minutes. Each treatment consisted of five replicates with approximately 30 embryos per replicate. Higher CPA concentrations reduced hatching rates, and toxicity increased in the order of PG
Aquaculture species are often exposed to disease challenges and environmental stress, necessitating the use of natural dietary supplements to enhance health and productivity. This study evaluated the effect of Ganoderma lucidum polysaccharide (GLP) on the growth performance, intestinal enzyme activity, serum antioxidant capacity, and disease resistance of the Chinese soft-shelled turtle (Pelodiscus sinensis) against Aeromonas hydrophila infection. A commercial diet (50% crude protein) was supplemented with GLP (50% purity) at 0 (GLP0), 2.5 (GLP25), 5 (GLP50), 7.5 (GLP75) and 10 (GLP100) g/kg feed. A total of 450 soft-shelled turtles (4.00 +/- 0.20 g) were randomly stocked into five concrete tanks (1.2 x 0.4 x 0.3 m) in triplicates and fed thrice daily (8:00, 13:00 and 18:00) at a feeding rate of 3-5% body weight for eight weeks, which was adjusted weekly. At the end of the feeding trial, the soft-shelled turtles were challenged with A. hydrophila (2.0 x 10(7) CFU/ml) by intraperitoneal injection. The results showed that the soft shelled turtles fed GLP50, GLP75 and GLP100 diets had significantly improved weight gain, specific growth rate, feed conversion ratio and survival (%) compared to those fed the control diet (p < .05). All GLP diets significantly enhanced intestinal trypsin and lipase activities, while the GLP50, GLP75 and GLP100 diets also improved intestinal alpha-amylase activity compared to the control (p < .05). The turtles fed GLP50 and GLP75 diets displayed significantly enhanced serum total superoxide dismutase activity compared to the control (p < .05). GLP supplementation significantly increased serum catalase and glutathione peroxidase activities while reducing serum malondialdehyde content (p < .05). The cumulative mortality decreased significantly at all levels of GLP supplementation after A. hydrophila challenge (p < .05). Polynomial (quadratic) regression analysis indicated optimum GLP levels of 8.33 g/kg for final body weight, 7.56 g/kg for trypsin activity, and 13.52 g/kg for glutathione peroxidase activity. In conclusion, dietary GLP supplementation enhanced growth, digestive enzyme activities, antioxidant capacity, and disease resistance in Chinese soft-shelled turtles, demonstrating its potential as a functional feed additive in aquaculture.
Consumer preferences shape demand for fish. However, empirical evidence on non-nutritional drivers of choice is scarce. This paper examines consumer preferences for intrinsic attributes of tilapia through a survey of 449 Nigerian consumers focused on red and black tilapia. The Implicit Association Test (IAT) was used to examine subconscious biases, and conjoint analysis to determine the relative importance of various fish attributes in consumer decision-making. Results from the IAT show a strong implicit preference for black tilapia, which was more closely linked to positive attributes such as freshness and taste. Color was the most influential factor in consumer decision-making, followed by production source and price. Preference patterns varied slightly by age, but not by gender or education. This paper highlights how visual biases and attribute prioritization can shape consumer demand in emerging markets. The finding insights for product positioning, species diversification and marketing strategies across similar contexts.
The present study was conducted to assess the effects of fresh and 30%, 40%, and 50% of dry Azolla pinnata as supplementary diets with the basal feed on the growth performance, growth-related gene expression, and antioxidant enzymes of Nile tilapia (Oreochromis niloticus) under normal conditions. Also, we evaluated their protective impact on these parameters against the toxicity of a heavy metal mixture (Cu, Pb, and Zn) for 5 weeks. An average initial body weight of O. niloticus, which was used, was 31.5 +/- 1.5 g. Three replicates were used for each treatment (10 fish/replicate). The results showed that O. niloticus exposed to heavy metals (HMs) and fed on fresh and 40% and 50% of dry A. pinnata had high significant levels of ghrelin, leptin, and the insulin-like growth factor gene (IGF-1) compared to untreated exposed fish (p < .05). Further, fresh and 40% and 50% of dry A. pinnata significantly decreased the accumulation of Cu, Pb, and Zn in the liver, intestine, and muscles of fish (p < .05). In addition, they led to a significant increase in antioxidant enzyme activities (p < .05) and reduced oxidative stress induced by heavy metal toxicity. Ultimately, our study concluded that the basal feed enriched with fresh and 40% and 50% of dry A. pinnata can effectively provide protection for O. niloticus against the toxic effects of HMs.
