Tropical Aquaculture is an international journal published continuously. It publishes original and previously unpublished Scientific Articles, Scientific Notes, and Review Articles, from researchers of any national or international educational institution or research center, in an electronic and printed open-access format. The journal aims to create a space for discussion and dissemination of results and advances of original and unpublished research on Aquaculture-related scientific developments in the tropics.
Control of horizontal transmission of white spot syndrome virus by ultraviolet light
Bacterial and viral diseases are common problems in aquaculture. The use of flow-through systems frequently represents a risk of contamination by introducing pathogenic microorganisms, resulting in diseases that economically damage the industry. White spot syndrome virus (WSSV) causes a shrimp disease responsible for substantial economic losses in many countries. The present study was conducted to determine if the specific pathogen-free (SPF) indicator shrimp might take WSSV from infected water flow after treatment with UV light: specific pathogen-free L. vannamei shrimp, 2.5-g avg Wt, were acclimated to 25 UPS artificial seawater. Once acclimated, they were distributed in four pairs of tanks (20/tank). Each pair of tanks had one tank infected by per os and one exposed to water from the infected tank. Water flow from the per os infected tank was pumped to the non-infected tank and returned to the per os infected tank by gravity. Two pairs of tanks had UV light (G15T8) to irradiate the flow of water before passing it to the non-infected tank. The other two pairs of tanks (control group) had no UV light irradiation to the recirculating water. Moribund and dead shrimp were collected and frozen to determine if they were infected with WSSV by using PCR. After 12 days of shrimp in, the tanks exposed to water contaminated with WSSV and treated with UV did not have any mortality. The water contaminated with WSSV and not treated with UV resulted in significant numbers of WSSV-infected and dead shrimp. This study demonstrated that it is possible to eliminate the transmission of WSSV by treating the water with UV.
Copyright (c) 2025 Tropical Aquaculture https://creativecommons.org/licenses/by-nc-nd/4.0
Totoaba, a species with great potential for mexican mariculture
The Totoaba (Totoaba macdonaldi) is a member of the Sciaenidae family, which includes croakers. It is the largest species in this family and is currently classified as an endangered species. Fishing for it has been permanently banned in Mexico since 1975 due to illegal fishing driven by the value of its swim bladder on the Asian market. This situation requires an honest evaluation by the relevant authorities.
Evaluation of cassava meal as substitute for wheat in the feeding Clarias gariepinus
Se evaluó la harina de yuca integral (HYI), como sustituto parcial de la harina de trigo (HT), en el pienso comercial de Clarias gariepinus durante la preceba. Se utilizaron 180 animales de 10,6 ±0,05 g de peso medio inicial, ubicados según diseño completamente aleatorizado en cuatro tratamientos con tres repeticiones y la prueba estadística de DUNCAN con 5% de probabilidad. Los tratamientos fueron el control, formulación del pienso comercial de bagres, y tres experimentales con HYI que representaron el 25, 50 y 75 % de sustitución del trigo del control. Los pellets con HYI tuvieron buena integración física y aceptación por los animales. No se encontraron diferencias en las cantidades de alimento (87,13, 85,80, 87,56 y 85,33 g) y proteína suministrados por animal (26,80, 24,82, 26,02 y 24,89 g). Tampoco hubo diferencias en los pesos finales (62,58, 60,28, 64,85, 60,25 g) y conversión alimentaria (1,65, 1,64, 1,59 y 1,68). Sin embargo, la mejor eficiencia proteica se obtuvo al sustituir el 50 % de trigo (1,96, 2,02, 2,10 y 2,00). La supervivencia fue 100 % en todos los tratamientos. Los costos de alimentación y beneficios económicos favorecieron todos los tratamientos con HYI. El mayor ahorro se alcanzó al remplazar 50 % de la HT ($ US 115,22 /t de pescado). Se concluye que la harina de yuca integral puede sustituir hasta el 75% de la harina de trigo en el pienso de alevines de C. gariepinus, sin comprometer el comportamiento productivo de los animales y con efecto económico positivo.
Hermaphroditism in fish, an opportunity in aquaculture
Hermaphroditism is defined as a reproductive strategy involving male and female functions in the same individual. This may occur simultaneously or sequentially, and it is present in the major taxonomic divisions of plants and is common in several Metazoans. In fish, these sexual transitions occur due to growth, survival, and reproductive trade-offs, and it has been documented in more than 450 species. In aquaculture terms, managing sex-changing species is complicated because the timing and causes of sex change in hermaphrodite fish are poorly understood, complicating planned reproductive events and meeting production goals. However, applying biotechnological processes such as sex reversal utilizing steroids could represent an advantage in obtaining organisms of the “desired” sex to obtain gametes and, therefore, make the use of aquaculture facilities more efficient.
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Genetic merit evaluation of second-generation Nile tilapia (GIFT)
The present study aimed to determine the genetic value of Nile tilapia GIFT in its second generation. The data evaluated corresponded to 19 families obtained from the genetic improvement program of tilapia in Cuba. An evaluation was performed on the entire population to determine each individual's genetic value, classifying it into high, medium, and low. The results obtained for high genetic merit were 362 and 322 grams for males and females, respectively, demonstrating the superiority of males over females for the live weight characteristic. The genetic parameters and variance components were estimated: additive, residual and phenotypic variance. As a fundamental element, heritability was estimated, characterized by being classified as high by obtaining a value of 0.49. The evaluation of genetic merit in genetic improvement programs represents a high potential to improve productivity through genetic selection.
Comparative study between live weight and sexual dimorphism in six generations of Nile tilapia GIFT
The present investigation focused on the results obtained to evaluate the traits of live weight and sex through comparative analysis based on the number of generations. A total of 86 groups of GIFT Nile tilapia families were obtained along six generations of the genetic improvement program in Cuba. It was observed how the average live weight of the fish increased when passing from one generation to the next. The best results were found in generations five and six with values greater than 500 g (514 g and 612 g, respectively). A regression analysis was performed, obtaining a coefficient of determination (R2) of 60.9 %, demonstrating that the generation and sex effects explain approximately 61 % of the phenotypic variability shown by the live weight trait. At the same time, the superiority of the males was evident since the beginning of the genetic improvement program, with an average weight of 776 g in the males and 470 g in the females. The main result was a significant increase in live weight in GIFT Nile tilapia with the advance of the selective program applied to both sexes, showing superiority for males.
Productive performance of Clarias gariepinus fed alternative diets
Due to the growing need for new food formulations with local ingredients, the productive behavior of 72 juvenile of Clarias gariepinus (100.16 ± 1.72 g initial weight) fed with different diets during the fattening period was evaluated. A completely randomized design of three treatments with three repetitions and Duncan significance test at 5 % probability was used. The treatments were the control (commercial food, AC) and two humid diets with fishery by-products and broken soybeans and as energy source, one with cassava meal (HY) and the other with wheat bran (ST). The amounts of crude protein supplied per fish were similar between the control and cassava meal diet (78.9, 77.0 y 88.4 g). Growth did not show differences between the diets (final weights of 291.43, 284.21 and 241.29 g). The feed conversion was unfavorable with the humid diets (1.23, 1.81 y 2.21), while the protein efficiency was the same for the control and the diet with cassava meal (2.41, 2.40 y 1.61). Survivals were 100% for all treatments. The economic analysis showed monetary savings due to feeding with humid diets ($ CUP 17,316 y 14,543), since they were made from by-products available in the territory and there was no significant variation in the zootechnical indicators. It is concluded that alternative diets promoted good productive behaviors in juveniles of C. gariepinus, with a positive economic effect.
Behavioral repertoire of Arapaima gigas (Schinz, 1822) reared in captivity and its implication for welfare protocols
The well-being of farmed fish has gained considerable attention in the last few decades, and finding suitable indicators of fish welfare is particularly challenging assumed the diversity of species, each with unique biological needs and requirements. Understanding the behavioral patterns of farmed fish species is crucial in developing behavior-based measures to maintain their welfare and production. However, there is limited scientific documentation on the behavioral repertoire of Arapaima gigas, a commercially valuable and widely farmed species in South America. We provide an ethogram of A. gigas when reared in captivity within a recirculating aquaculture system (RAS) indoors. Observations were conducted on a group of adult individuals (one male, two females) kept at the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin, Germany. The ethogram describes five main behavioral categories: locomotion, feeding, social interactions, agonistic interactions, and breathing. Notably, Arapaima displayed a strong preference for resting motionless, often near a gravel bed area provided inside the rearing tank. Agonistic interactions were rare and mostly initiated solely by the male during feeding sessions. During feeding, pellet food was often picked from the ground, while whole fish feed (dead Tilapia) was mostly swallowed immediately from the surface. The male consistently occupied the provided gravel area as its territory, spending most of its time there. With this ethogram, we aim to contribute to the limited behavioral knowledge about A. gigas, especially when in captivity. Our findings offer valuable insights into species-specific welfare evaluations and enhancement measures with potential applications in healthy aquaculture practices.
Spawning Induction, Larviculture and Rearing of Mexican Snook Centropomus poeyi (Chávez, 1961)
The Mexican snook (Centropomus poeyi) constitutes an essential artisanal fishery in coastal areas of Mexico containing rivers that discharge into the Gulf of Mexico, and it is considered overfished in general; therefore, aquaculture can provide alternatives to this situation. Induced spawning and Larviculture have been developed in our laboratory for this critical endemic species. Using cholesterol-cellulose implants with LHRH-a, spawning is initiated 30 hours after implantation. A total of 9.5 million fertilized eggs were collected, averaging 700.35 µm in diameter. The fertilization rate was 90%, and the hatching rate was 85%. Two hundred thirteen thousand fish were fed according to a protocol generated for this species, using microalgae, rotifers, and Artemia nauplii. Weaning is initiated 15 days post-hatching using a co-feeding regime combining live food and inert diets designed for marine fish. Survival at the end of the larval period was 1.8%, with fish feeding exclusively on artificial food and acclimated to freshwater.
Feeding the Future: The role of aquaculture in the tropics
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History and Perspectives of Mariculture in Mexico
Cultivo de Oreochromis niloticus y Tradescantia zebrina en Sistema Acuapónico, una Evaluación de Coliformes Fecales
La acuaponía ofrece una forma de producir alimentos frescos de manera sostenible, si no se maneja adecuadamente puede haber riesgos de contaminación con coliformes fecales. Este estudio evaluó la presencia de coliformes fecales en sistemas acuapónicos a pequeña escala utilizando Oreochromis niloticus (tilapia) y Tradescantia zebrina (matalí) como organismos modelo. Se compararon tres sistemas acuapónicos equipados con biofiltros con tres sistemas de acuicultura de recirculación cerrada sin biofiltros, que sirvieron como grupos de control. Cada sistema acuapónico de 200 L estaba dividido en dos áreas: una zona de acuicultura para la tilapia y una zona hidropónica para el matalí. En la zona hidropónica, se utilizó tezontle como medio para el biofiltro que remedia el agua contaminada con desechos de peces. Se midieron parámetros como el amoniaco, nitrito, nitrato, pH, oxígeno disuelto, temperatura, y la presencia de coliformes fecales fue determinada según la norma 042 (SCFI,2015) Los análisis estadísticos se llevaron a cabo mediante la prueba Kruskal-Wallis. Los resultados indicaron que los biofiltros redujeron la presencia de coliformes fecales en un 98% en la zona de acuicultura y en un 90% en el agua de salida de la zona hidropónica. Los niveles de coliformes en los sistemas acuapónicos se mantuvieron por debajo del límite de detección (<3 NMP/100 mL), mientras que en los sistemas de acuicultura de control se registró una mayor presencia de estos microorganismos.
Effect of Saccharomyces cerevisiae on growth performance and hematological parameter in commercial tilapia culture
In Mexico, fish farming is moving towards a trend towards sustainability, which means that production and the products obtained increase in quality and quantity, reducing the environmental impact. The objective of the present study was to evaluate the effect of Saccharomyces cerevisiae (commercial probiotic Blue Booster®) through two treatments under a completely randomised design; 36 broodstock/m3 were stocked in 69 m3 geomembrane ponds, which were supplied with Saccharomyces cerevisiae yeast for 150 days at a concentration of 1x109 CFU mL-1 and a Control treatment (CT) without the addition of the yeast. Growth and haematological variables were determined in the fish, and water quality parameters were determined. Water quality remained within the ranges considered normal for the species' culture, showing that the Blue Booster® (BB) treatment had better growth performance and water quality. Yeast-treated fish showed an average weight of 499.0 g (± 59.6), with an average length of 26.1cm (± 1.36), being significantly different from the Control treatment (p< 0.05). It was observed that the hematocrit percentage was higher for the BB treatment, at 44.3%, and survival was 94.0%. The results showed that with the application of this probiotic technology, the water quality is maintained in optimal conditions and the productive parameters are improved, in addition to reducing the frequency of water replacement in the culture ponds, which is a direct benefit for the producer.
An overview of feeding strategies and challenges in tropical aquaculture
Feeding accounts for more than 50% of the operating costs of commercial tropical aquaculture species such as tilapia and shrimp, while costs are difficult to estimate for emerging species, such as snooks and native cichlids, which are still under biotechnological development. Optimizing diets and feeding practices is essential to ensure the profitability and sustainability of the growing aquaculture industry. Specialized diets for critical stages such as reproduction and larval rearing are costly but justified by improved offspring quality and larval growth. However, the lack of specific feeds for emerging species forces the use of generic diets, such as those developed for tilapia or trout, which may not meet optimal nutritional requirements. This approach limits the productive evaluation of these species and, in the long term, the development of specific diets for commercialization. Dietary improvements include new ingredients and technological processes that increase efficiency, reduce costs, and minimize environmental impact. For example, the inclusion of animal meals has improved the acceptability of diets for carnivorous species. However, the design of feeding protocols remains challenging, particularly for larvae where live feed is common but costly. Genetics and environmental management are determining factors in the production performance of commercial species. In Mexico, the limited genetic acclimatization of imported tilapia has led to challenges such as diseases and stress episodes that affect growth and discourage investment. Integrating biotechnologies such as probiotics and prebiotics has shown benefits in the integrated management of the culture, reducing stress, improving feed efficiency, and reducing environmental impact. It is necessary to emphasize the generation of informed strategies that consider local resources and global information to minimize environmental and social risks and promote responsible and sustainable aquaculture that balances economic, social, and environmental benefits.
First record of the Lymphocystis Mayaheros uropthalmus in Balancán, Tabasco, México.
A new record for freshwater environments is reported in six organisms of the native species Mayaheros urophthalmus collected in the municipality of Balancán, Tabasco, Mexico. It represents the first record of this viral lymphocytic infection in a native cichlid of economic and ecological importance. Its presence indicates the status of aquaculture health in the area, due to the time of year, its incidence or degree of infection responds to its environmental distribution influenced by temperature, stress and environmental contamination.
The Mayan Cichlid, Mayaheros urophthalmus : Native Mesoamerican species, with high aquaculture potential
Aquaculture allows food production, bringing important social and economic benefits that result in high nutritional value and accessible costs for the population. Mexico has a great diversity of native species with great potential for this activity, such as the Mayan cichlid, Mayaheros urophthalmus. The present bibliographic review was carried out in Google Scholar, libraries and the institutional repository of the Universidad Juárez Autónoma de Tabasco on the advances in the knowledge of the biology, fishery and aquaculture potential of the mojarra castarrica. Among the results, it was found that 60% of them are focused on the biology and ecology of the species, highlighting that it is an omnivorous fish with a carnivorous tendency that normally feeds on fish and invertebrates, presents an important fecundity, reproducing several times during the warm months. The fishery status of the beaver is uncertain; at present, catches are reported as encompassing all cichlids, so there is no basis to indicate its status. However, fishermen report low catches. In aquaculture, there are advances in culture, nutrition and biotechnological aspects, with larval culture being identified as one of the critical phases of development. In the grow-out stage, it can be cultivated in cages, geomembranes or earthen ponds, using a feed containing between 32 and 45% protein. Progress has been made in nutrition, but there is still no feed specifically designed for this species. Many more studies are required to determine its fishing and aquaculture potential.
Stock density, feeding, and water salinity for larval rearing of yellowtail tetra (Astyanax altiparanae)
One of the critical points in fish rearing is larviculture, a phase that requires suitable food for first feeding. The aim of this study was to evaluate the effect of three variables on the larviculture of the yellowtail tetra Astyanax altiparanae: 1) type of Artemia franciscana nauplii used for feeding (Fresh, frozen and freeze-dried); 2) salinity (0.2%, 0.4%, and 0.6% NaCl); and 3) stocking density (50, 100, 150, and 200 larvae/L-1). Growth and survival were evaluated over 10 days. On day 10, larvae fed with Artemia nauplii (fresh) had a higher length and survival rate when compared with other treatments (P= 0.0012). Water at 0.4% and 0.6% NaCl showed significantly (P = 0.0010) lower and no survival, respectively. Lower density (50 larvae L-1) showed the greater length (7.73 ± 0.08 mm) and the highest density (200 larvae L-1) presented the lower length (5.86 ± 0.10 mm). These results are innovative for this species, opening up new larviculture possibilities for laboratory and aquaculture purposes.
Performance of seven lines of Nile tilapia Oreochromis niloticus in cages and conventional ponds
Two experiments were conducted to evaluate the performance of seven lines of Nile tilapia, Oreochromis niloticus, provided by various farms in the region. Performance was measured and compared among lines as: growth, survival, masculinization rate and health status. For the first experiment, we evaluated seven tilapia lines; fish were randomly allocated in triplicate 2x1x1m-floating cages at an initial density of 1000 fish per cage. Densities were adjusted as the fish grew. The results showed significant differences (p <0.01) in growth and survival. Health status showed differences as well. In the second experiment, we evaluated the top four lines of the first experiment. In this case, fish were stocked in duplicate at random in 10x5x1m-concrete ponds at a density of 1000 fish per pond. The density was reduced to 500 fish per pond half time through the experiment. The results indicate that the lines Tabasco and Chitralada had the highest final weight with 301.11 and 291.30g, respectively; an FCA of 1.1 for both lines, a survival of 95%, and a masculinization rate around 99.4%. In terms of health indicators, we identified the presence of different species of bacteria and parasites in all lines tested.
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Manipulated Photoperiod Enhances Sperm Production and Quality in Male Gray Snapper Lutjanus griseus (Linnaeus, 1758): A Potential Approach for Tropical Aquaculture
Photoperiod manipulation has been used as an alternative non-invasive method to stimulate sexual maturation in fish. It consists mainly in influencing spatially and temporally the physiological control of the animal over its reproductive period. There are few studies on the effect of photoperiod in male fish and much less for tropical climates. Because of this, the present study focused on inducing gonadic maturation in male grey snapper (Lutjanus griseus), manipulating the duration of the sexual maturation season of five months into two months; the compressed months were March to July. From the fourth week of March (12h and 30 min light), adjustments of 2.4 minutes per day were made until reaching the hours of light corresponding to the maximum estimated peak in the year (13h and 42 min light). All fish confined under artificial photoperiod had a significant response in sperm production. In addition, greater fluidity and greater sperm motility were observed, with a higher number of sperm cells than in the natural photoperiod. These results will allow extending the months of reproductive management of this species using controlled photoperiod.