The golden apple snail, Pomacea canaliculata, locally known as golden kuhol, is native to South America and was introduced to the Philippines between 1982 and 1984, where it quickly became notorious for devouring young rice plants. But the snail is also remarkably protein-rich, and its foot tissue meal, abbreviated GASFTM, offers high protein content at a fraction of the cost of squid meal, the expensive main protein ingredient in conventional broodstock maturation diets. Compound diets have long been attractive to hatchery managers because they are easier to manage and store and are less susceptible to pathogenic contamination than fresh feeds, but formulating adequate diets has been hampered by poorly defined nutritional requirements for shrimp broodstock, and artificial diets have so far delivered less promising results than raw feeds. The new study set out to evaluate whether GASFTM could serve as a viable alternative protein source in the gonad maturation diet of female P. vannamei broodstock, potentially replacing squid meal entirely.

The experimental design was rigorous. Mature golden apple snails were gathered from Barotac Nuevo in Iloilo, Philippines, and their raw tissues were washed, boiled, and separated from the shells. The collected foot tissues were dried, ground, and sifted through a 100 micrometer sieve to produce a powdered snail meal that was incorporated into the maturation diet as a substitute for squid meal. Ninety female P. vannamei broodstock, each weighing approximately 30 grams and aged six months, with translucent ovaries, were obtained from the University of the Philippines Visayas Multi-Species Hatchery, where they had been reared on formulated feeds from the early juvenile stage. After a seven-day acclimation period on a control diet, all females in the intermolt stage were unilaterally eyestalk-ablated by tying the eyestalks with surgical thread and marked with eye tags for individual identification, a standard endocrine manipulation that accelerates ovarian development in penaeid shrimp.

The ablated females were randomly allocated at a density of 15 individuals per 6 cubic meter rounded maturation tank, with one tank assigned for each treatment in a completely randomized design with three replicates. Five isonitrogenous and isolipidic experimental diets were formulated containing increasing levels of GASFTM: a control with 0 percent, and test diets with 25, 50, 75, and 100 percent inclusion replacing squid meal on a gram-for-gram basis. Frozen polychaetes and squid served as the positive control, while a basal diet served as the negative control. The diets were designed to meet the nutrient requirements for P. vannamei broodstock, with crude protein levels around 45 percent and crude lipid around 13 to 15 percent across treatments, based on a previous formulation described by Paibulkichakul and colleagues in 2008. Cholesterol, soybean lecithin, fish oil, vitamin premixes, and mineral mixes were adjusted to keep the diets nutritionally balanced as the snail meal content rose. The shrimp were fed at 10 percent of their body weight three times a day for 32 days, with excess feed, feces, and exuviae removed each following morning.

Water quality was carefully maintained throughout the trial at the Miagao, Iloilo hatchery: temperature at 27 to 28 degrees Celsius, salinity at 28 to 33 ppt, pH at 8.0 to 8.5, dissolved oxygen above 5 milligrams per liter, ammonia nitrogen below 0.5 milligrams per liter, and nitrite below 0.1 milligrams per liter. Water depth was held at 0.50 meters with a total daily water replacement of 30 percent using filtered seawater, and the photoperiod followed a natural cycle of 13 hours light and 11 hours dark. Ovarian development was tracked every four days by measuring body width and ovary shadow width at the dorsal exoskeleton of the first pleonite with a caliper. Only females at an early stage of ovarian development, with an initial ovary shadow ratio between 22 and 27 percent, were randomly selected for all treatments. Ovarian maturation time was defined as the mean days elapsed for shrimp ovaries to develop from the initial to the maximum ovary shadow ratio, ranging from 40 to 45 percent.

The results were striking. The maximum ovary shadow ratio, a measure of ovarian size, was not significantly different among the treatments, indicating that all diets supported comparable ultimate ovarian development. But ovarian maturation time told a different story: the test diets with 50, 75, and 100 percent GASFTM produced significantly shorter maturation times than the basal diet and the 25 percent GASFTM groups. The 75 percent GASFTM diet delivered the fastest maturation at 7.8 days, followed by the 100 percent diet at 9.7 days and the 50 percent diet at 9.9 days, compared with 14.1 days for the polychaete and squid positive control and 14.6 days for the 25 percent GASFTM group. The study concluded that diets with 75 and 100 percent GASFTM inclusion were the most effective on P. vannamei ovarian maturation, followed by the 50 percent diet.

Reproductive performance measures showed no significant differences among the test diets, but the groups fed with polychaetes and with diets containing 50 and 75 percent GASFTM showed the highest total egg production and spawning rates. The 50 and 75 percent GASFTM groups achieved spawning rates of 53.33 percent, compared with 46.60 percent for the polychaete and squid positive control and 40.00 percent for the basal diet. Total egg production in the 75 percent GASFTM group reached approximately 118,861 eggs, the highest among all treatments. Survival rates of female broodstock did not differ significantly across diets, and growth performance was similarly unaffected: final mean body weight, specific growth rate, and feed conversion ratio showed no significant differences between the test diets and the control group. The group fed with polychaetes and the 75 percent GASFTM group had the highest mean body weight after 32 days, at 39.50 grams.

The nutritional explanation lies in the amino acid and mineral profile of the snail tissue. In sexually maturing animals, feed protein requirements are believed to be higher than during non-reproductive stages because intense biosynthesis occurs during these processes. Currently, maturation diets contain at least 44 percent protein, but still lower than the protein content of diets based on fresh food. The dietary provision of essential amino acids has been reported to be crucial for the success of maturation and spawning in crustaceans, with ten amino acids identified as essential for P. japonicus and similarly required in other penaeid species: arginine, methionine, valine, threonine, isoleucine, leucine, lysine, histidine, phenylalanine, and tryptophan. Golden apple snail is an ideal protein source for aquatic organisms because of its high content of these essential amino acids, especially lysine and methionine. Earlier work documented that the level of arginine in golden apple snail meal was higher than in fish meal, while leucine and threonine contents were comparable with fish meals, and lysine and tryptophan were found higher in the snail meal than in all other feed ingredients evaluated. The snail’s protein content of about 54 percent and its good essential amino acid profile are comparable with those of fish and squid meal.

Minerals may also play a role. Pomacea canaliculata has a high content of minerals and vitamins, with phosphorus reported at 35 percent and 1.2 percent in different measures. Earlier works on crustacean breeding have shown that mineral deficiencies or imbalances can inhibit crustacean reproduction, and mineral malnutrition can change the composition and quality of the eggs. Minerals are important in minimizing the impacts of stress that can lead to oocyte resorption or reduced reproductive fitness in shrimp broodstocks. Squid meal includes significant amounts of phosphorus and sulfur, two elements involved in various salts, proteins, phospholipids, and other compounds, and marine waters and sediments allow squid to accumulate small amounts of other minerals such as calcium, magnesium, zinc, copper, iron, and manganese. The complete replacement of squid meal with GASFTM to promote ovarian maturation could therefore be attributed in part to the mineral contents of this ingredient.

Beyond the laboratory, the implications are considerable. Golden apple snails can be obtained in large quantities and continuously to meet various needs such as animal feed and fish feed. They flourish in a variety of public waters, have quick growth and reproduction, and are relatively easy to maintain, including in aquaculture ponds. The present work demonstrates that a formulated diet containing golden apple snail could be used as a maturation diet comparable to the effect of using fresh raw feeds, polychaete, and squid in promoting ovarian maturation of P. vannamei broodstocks. This could lessen the dependence of shrimp hatcheries on fresh feeds that can introduce diseases to the hatchery and lead to significant economic and production losses. The findings suggest that complete replacement of squid meal with GASFTM in broodstock maturation diets does not compromise either ovarian maturation or reproductive performance, offering a sustainable, locally available, and inexpensive protein ingredient for an industry under pressure.

Subject of Research: Aquaculture Nutrition

Article Title: Evaluation of foot tissue meal of golden apple snail, Pomacea canaliculata ( Gastropoda , Ampullariidae ), as an ingredient in the gonad maturation diet of female shrimp Penaeus vannamei ( Malacostraca , Penaeidae ) broodstocks

Article References: Pagapulan, M. J. B. B., Traifalgar, R. F. M., Lumayno, S. D. P., Huervana, F. H., & Gomez, D. K. (2025). Evaluation of foot tissue meal of golden apple snail, Pomacea canaliculata (Gastropoda, Ampullariidae), as an ingredient in the gonad maturation diet of female shrimp Penaeus vannamei (Malacostraca, Penaeidae) broodstocks. Acta Ichthyologica et Piscatoria, 55, 139-144. https://doi.org/10.3897/aiep.55.133988

Image Credits: AI Generated

DOI: 10.3897/aiep.55.133988

Keywords: aquaculture, shrimp farming, golden apple snail, broodstock nutrition, ovarian maturation, Penaeus vannamei, feed formulation, invasive species, Evaluation, foot, tissue, meal

The research, conducted by Jaynos R. Cortes of North Eastern Mindanao State University in the Philippines and Brett Laudato of VDS N.V. in Belgium, set out to evaluate the effects of a dietary additive blend containing choline chloride, L-carnitine, glycerol monolaurate, and lysophospholipids on growth performance, feed utilization, morphometric condition, growth uniformity, allometric growth, and low-salinity stress tolerance in juvenile P. vannamei. Rather than examining each additive in isolation, the study was designed to assess the overall response to the combined formulation, reflecting how such blends are deployed in commercial feed manufacturing. The team hypothesized that supplementation would primarily enhance nutrient-use efficiency, as reflected by improvements in protein efficiency ratio (PER) and feed conversion metrics, and that these metabolic gains might be associated with favorable changes in growth uniformity, morphometric condition, and tolerance to acute low-salinity stress.

The experimental design was rigorous and controlled. Juvenile shrimp, obtained from White Panther Hatchery in Austria and acclimated in a recirculating aquaculture system at VDS N.V. in Belgium, were stocked at a mean initial body weight of 0.90 grams into 500-liter HDPE tanks, with 80 shrimp per tank. Two dietary treatments were compared over a 42-day feeding trial: a control diet and an additive-supplemented diet, each assigned to four replicate tanks. Both diets were formulated to contain approximately 42 percent crude protein and 7 percent crude fat, ensuring that any observed differences could be attributed to the additive blend rather than to underlying nutritional disparities. The supplemented diet contained choline chloride at 0.30 percent, L-carnitine at 0.05 percent, glycerol monolaurate at 0.07 percent, and lysophospholipids at 0.05 percent. Water-quality parameters, including temperature, salinity, dissolved oxygen, and nitrogenous waste compounds, were monitored throughout the trial and remained comparable between treatments, confirming that environmental conditions did not confound the dietary comparison.

The four additives were selected for their complementary mechanisms of action in lipid digestion, transport, and utilization. Choline chloride functions as a lipotropic factor involved in phospholipid synthesis and lipid transport, facilitating the movement of fats through the body. L-carnitine plays a critical role in mitochondrial physiology, shuttling long-chain fatty acids into the cellular powerhouses where they undergo beta-oxidation to produce energy. Lysophospholipids enhance lipid emulsification and nutrient absorption in the digestive tract, potentially improving intestinal morphology and feed utilization. Glycerol monolaurate has been associated with improved intestinal health and nutrient absorption. Together, these compounds were designed to support the efficiency with which dietary nutrients are digested, absorbed, and converted into growth and maintenance processes, with the potential to reduce reliance on amino acids as energy substrates and thereby exert a protein-sparing effect.

After 42 days, the results painted a nuanced picture. The most striking finding was that dietary supplementation significantly increased the protein efficiency ratio compared with the control treatment, rising from 0.0221 to 0.0237, a statistically significant improvement of approximately 7.2 percent. This was the only significant treatment effect detected among the measured growth and feed-utilization variables. In contrast, survival remained high and comparable between treatments, averaging 93.75 percent in the supplemented group and 92.19 percent in the control. Final biomass, final mean body weight, and final body length were similarly unaffected. The feed conversion ratio was numerically lower in the supplemented group at 1.35 compared with 1.46 in the control, representing an improvement of approximately 7.5 percent, but this difference did not reach statistical significance, likely due to the limited number of tank replicates available for comparison.

Beyond the headline growth metrics, the researchers examined a battery of complementary phenotypic indicators that are often overlooked in conventional aquaculture nutrition studies. Growth uniformity, measured by the coefficient of variation for both weight and length, showed no significant differences between treatments, indicating that the additive blend neither enhanced nor disrupted competitive interactions among shrimp within culture tanks. Morphometric condition, assessed through modified condition factor and allometric growth coefficient, remained unchanged. Length-weight relationships, described by the power function W = aL^b, revealed approximately isometric growth patterns in both treatments, with allometric coefficients of 2.948 for the supplemented group and 3.126 for the control, neither differing significantly from the theoretical isometric value of 3.0. Analysis of covariance detected neither a significant treatment effect nor a significant treatment-by-length interaction, demonstrating that dietary supplementation did not alter the fundamental scaling relationship between body length and body weight.

To probe the physiological resilience of the shrimp, the team subjected ten randomly selected individuals from each tank to an acute low-salinity challenge at the end of the feeding trial. Shrimp were transferred directly into test tanks containing water at 0.35 parts per thousand salinity, a level approaching freshwater conditions that was selected to induce severe osmotic stress and maximize the ability to detect potential treatment-related differences in survival. However, because the challenge water temperature was approximately 14 degrees Celsius lower than the culture temperature maintained during the feeding trial, the shrimp were exposed simultaneously to both osmotic and thermal shock. Kaplan-Meier survival analysis and Cox proportional hazards modeling revealed no significant differences in mortality risk between treatments, with a hazard ratio of 1.34 for the supplemented group whose confidence interval encompassed unity. The authors caution that the combined nature of the stressor means any effects of dietary supplementation on salinity tolerance specifically may have been masked by the concurrent thermal challenge.

Multivariate and exploratory modeling analyses provided converging evidence for the study’s central conclusion. Principal component analysis revealed that the first two principal components explained 75.1 percent of the total variance, with protein efficiency ratio and feed conversion ratio contributing most strongly to the multivariate structure. Tanks receiving the additive-supplemented diet tended to be associated with higher PER values and lower FCR, whereas variation in body condition and growth uniformity contributed to differences among individual tanks regardless of treatment. Standardized path analysis and Random Forest classification, though limited by the availability of only eight tank-level experimental units, consistently identified protein efficiency ratio as the variable most strongly associated with dietary supplementation. These exploratory approaches, while hypothesis-generating rather than confirmatory, reinforce the univariate results and suggest that nutrient-use efficiency may be a more sensitive indicator of dietary additive responses than conventional growth metrics.

The authors acknowledge several important limitations when interpreting their findings. The use of four replicate tanks per treatment, while consistent with many controlled shrimp nutrition trials, limits statistical power to detect small-to-moderate treatment effects. The slight difference in analyzed crude protein content between the experimental diets, 42.06 percent in the control and 42.54 percent in the supplemented diet, cannot be completely excluded as a minor contributor to the observed PER response. Additionally, shrimp used in the survival analysis originated from replicated culture tanks, yet tank identity was not incorporated into the survival models, meaning the stress-tolerance results should be regarded as exploratory. The authors also note that feed intake values represent apparent feed intake derived from cumulative feed allocation rather than direct measurements of consumption, as uneaten feed was not quantitatively recovered.

From a practical perspective, the observed improvement in protein utilization efficiency carries meaningful implications for intensive shrimp production systems. Dietary protein is typically the most expensive component of shrimp feeds, and enhanced protein retention could contribute to reduced nitrogen excretion, lowering the environmental footprint of aquaculture operations. Even modest improvements in nutrient-use efficiency may therefore have both economic and environmental value. However, the absence of significant effects on growth performance, morphometric condition, growth dynamics, and low-salinity stress tolerance indicates that the benefits of supplementation are likely to be subtle and primarily related to nutrient utilization rather than broad enhancements of shrimp performance. The authors call for future studies incorporating longer feeding periods, larger sample sizes, temperature-controlled stress challenges, and factorial or dose-response designs to clarify the mechanisms underlying the observed responses and determine whether improved protein-use efficiency can translate into economically meaningful production benefits under commercial farming conditions.

Subject of Research: Effects of a functional feed additive blend on protein efficiency ratio, growth performance, and stress tolerance in juvenile whiteleg shrimp

Article Title: Effects of functional additive blend containing choline chloride, L-carnitine, glycerol monolaurate, and lysophospholipids on protein efficiency ratio, growth performance, and stress tolerance in juvenile Penaeus vannamei

Article References: Cortes, J. R., & Laudato, B. (2026). Effects of functional additive blend containing choline chloride, L-carnitine, glycerol monolaurate, and lysophospholipids on protein efficiency ratio, growth performance, and stress tolerance in juvenile Penaeus vannamei. Frontiers in Aquaculture, 5, Article 1909583. https://doi.org/10.3389/faquc.2026.1909583

Image Credits: AI Generated

DOI: 10.3389/faquc.2026.1909583

Keywords: Penaeus vannamei, whiteleg shrimp, aquaculture, feed additives, choline chloride, L-carnitine, lysophospholipids, glycerol monolaurate, protein efficiency ratio, nutrient-use efficiency, stress tolerance, feed conversion ratio

Humic acids are large, complex organic molecules formed through the microbial and chemical decomposition of plant and animal matter over geological timescales. Leonardite, a soft, oxidized form of lignite coal, is one of the richest natural sources of these compounds. In livestock nutrition, humic substances have a reputation for improving gut health, nutrient absorption and stress tolerance, and aquaculture researchers have increasingly wondered whether the same benefits translate to shrimp. The new study set out to answer a deceptively simple question: does supplementing feeds with leonardite humic acid, abbreviated LHA, change how juvenile shrimp use protein and lipid, and can it blunt the oxidative damage that can accumulate in intensively fed animals?

To find out, the research team designed a rigorous 3 × 3 factorial experiment. Nine experimental diets were formulated, spanning three levels of crude protein (360, 330 and 300 grams per kilogram), three levels of lipid (50, 70 and 90 grams per kilogram) and three levels of LHA supplementation (0, 9 and 12 grams per kilogram). The diets also varied systematically in digestible energy, ranging from roughly 374 to 398 kilocalories per 100 grams, creating a matrix in which the independent and combined effects of nutrient density and humic acid could be disentangled. Each diet was assigned to triplicate groups of shrimp, with 675 juveniles weighing about 5.02 grams at the start of the trial randomly distributed across the tanks.

The outcome was remarkably clear. Shrimp fed the intermediate-protein, intermediate-lipid diet supplemented with the highest dose of humic acid, a formulation labeled P33L7LHA1.2, delivered 330 grams of crude protein and 70 grams of lipid per kilogram along with 12 grams of LHA, outperformed every other group. These animals recorded the highest weight gain, the highest specific growth rate, and the best protein and lipid efficiency ratios, meaning they converted dietary protein and lipid into body tissue more effectively than their peers. At the same time, they showed the lowest feed conversion ratio, the widely used efficiency metric that every shrimp farmer watches closely, alongside the highest whole-body protein content and, notably, the lowest whole-body lipid content and hepatopancreas somatic index, a measure of the relative size of the shrimp’s central metabolic organ.

That combination, faster growth with leaner bodies and a smaller relative hepatopancreas, points to a genuinely improved metabolic state rather than simple overfeeding. In crustaceans, the hepatopancreas performs the functions of a liver and pancreas combined, secreting digestive enzymes, storing energy reserves and orchestrating lipid metabolism. When the organ enlarges, it often reflects a heavy lipid-handling burden. A lower index combined with superior growth suggests the shrimp in the LHA-supplemented groups were processing their feed with less metabolic strain, a finding with direct implications for both productivity and animal welfare in intensive systems.

The digestive enzyme data reinforced this picture. Amylase and lipase activities in the hepatopancreas rose significantly as dietary lipid levels increased, while protease activity followed the opposite trajectory, peaking in the group fed the intermediate protein-lipid ration and falling to its lowest in animals receiving the high-lipid, low-protein diet. Critically, LHA supplementation enhanced the activity of all three digestive enzymes at every dietary level, with the strongest responses observed at the 12 gram per kilogram dose. The researchers also measured two key lipid metabolic enzymes, glucose-6-phosphate dehydrogenase and carnitine palmitoyltransferase-1, both of which reached their maximum activities in the P33L7LHA1.2 group and their minimum in shrimp receiving the low-lipid diet without humic acid. Elevated activity of these enzymes indicates more efficient mobilization and oxidation of fatty acids, consistent with the leaner body composition of the best-performing animals.

Perhaps the most striking results concerned oxidative stress. Shrimp, like all aerobic animals, generate reactive oxygen species during normal metabolism, and high-lipid diets can accelerate their production, damaging cell membranes and taxing the animal’s antioxidant defenses. The trial tracked the activity of superoxide dismutase and catalase, the two frontline antioxidant enzymes, in both the hepatopancreas and the gills. As dietary lipid increased, hepatopancreatic antioxidant enzyme activities declined while branchial activities rose, revealing a tissue-specific redistribution of defensive capacity. LHA supplementation, however, reduced the activities of both enzymes across the board, with the lowest values again recorded in the group receiving the highest humic acid dose alongside the intermediate protein-lipid ration.

At first glance, lower antioxidant enzyme activity might seem undesirable, but the accompanying biochemical markers tell a different story. Shrimp fed 12 grams per kilogram of LHA displayed the lowest levels of malondialdehyde, the standard biomarker of lipid peroxidation and membrane damage, together with the lowest circulating glucose, cholesterol and triglyceride concentrations. Reduced malondialdehyde despite reduced antioxidant enzyme activity implies that the animals were experiencing less oxidative insult in the first place, requiring a less activated defense system. In other words, humic acid appears to have lightened the oxidative load itself rather than merely forcing the antioxidant machinery to work harder, a distinction that matters enormously for long-term health and stress resilience in farmed shrimp.

The metabolic blood markers add a further layer of insight. Lower plasma glucose suggests a calmer stress response, since glucose mobilization is a classic endocrine signature of physiological stress in crustaceans. Reduced cholesterol and triglyceride levels, meanwhile, align with the enhanced lipid-oxidizing enzyme activities and the lower whole-body lipid deposits, painting a coherent metabolic portrait of animals that were absorbing nutrients efficiently, burning lipid effectively and carrying less metabolic baggage. Taken together with the growth and feed efficiency data, the trial makes a strong case that humic acid is not merely a passive feed additive but an active modulator of shrimp physiology.

The practical conclusion of the study is straightforward: among the nine diets tested, the formulation containing 330 grams per kilogram of crude protein, 70 grams per kilogram of lipid and 12 grams per kilogram of leonardite humic acid produced the most favorable growth performance and antioxidant responses in juvenile P. vannamei reared in inland saline water at 10 parts per thousand. For an industry pushing into inland regions and simultaneously hunting for sustainable, non-antibiotic feed additives, the findings arrive at an opportune moment. Leonardite is an abundant, inexpensive natural resource, and if humic acid supplementation can reliably improve feed conversion, reduce fat deposition and dampen oxidative stress at a modest inclusion level, it could become a standard component of shrimp feeds in saline aquaculture systems worldwide. The researchers caution that their results apply to juveniles over a 60-day window, and further work will be needed to confirm the benefits across full production cycles, but the direction of the evidence is unmistakable. A coal-derived organic compound, of all things, may soon help shrimp thrive in water that farmers once considered worthless.

Subject of Research: Effects of dietary leonardite humic acid on growth, lipid metabolism and antioxidant status of juvenile white-leg shrimp in inland saline water

Article Title: Leonardite humic acid enhances growth, lipid utilization and antioxidant status in juvenile Penaeus vannamei

Article References: Das, R., Sahu, N. P., Sardar, P., Jana, P., Varghese, T., Deo, A. D., Bedekar, M. K., Nanda, C., & Bhusare, S. (2026). Leonardite humic acid enhances growth, lipid utilization and antioxidant status in juvenile Penaeus vannamei. Frontiers in Aquaculture, 5, Article 1840408. https://doi.org/10.3389/faquc.2026.1840408

Image Credits: AI Generated

DOI: 10.3389/faquc.2026.1840408

Keywords: Penaeus vannamei, leonardite humic acid, aquaculture nutrition, inland saline water, lipid metabolism, antioxidant status, feed conversion ratio, hepatopancreas, digestive enzymes, shrimp farming, protein-lipid diets, oxidative stress

The stakes are considerable. Shrimp aquaculture has become one of the fastest-growing food production sectors on the planet, and India sits at its center. The country ranks third in global aquaculture output after China and Indonesia, accounting for 7.70 percent of world production, and its sector has posted double-digit annual growth exceeding 10 percent over the past decade. Yet the industry’s Achilles heel lies at the very start of the production line: hatcheries that supply healthy seed stock. Poor quality larvae during the initial stages constrain survival, growth, and ultimately the productivity of entire farming operations downstream.

Conventional shrimp hatcheries solve their water quality problems the old-fashioned way—by flushing. Large volumes of water are exchanged continuously to keep toxic nitrogenous wastes in check, a strategy that carries heavy costs in pumping, collection, filtration, and disinfection, while also creating pathways for disease and discharging nutrient-rich effluent into the environment. Biofloc technology, or BFT, offers a fundamentally different approach. Instead of removing nitrogenous waste, the system recruits communities of heterotrophic bacteria to convert it into microbial biomass. By manipulating the carbon-to-nitrogen ratio in the water, farmers encourage these bacteria to proliferate, forming dense suspended aggregates—the flocs—that shrimp can graze on as a natural, continuously available food source.

The catch is that bacteria need carbon to do this work, and not all carbon sources are created equal. Simple sugars such as molasses, glucose, and fructose are rapidly degraded, while complex materials like rice bran and cellulose break down slowly. The choice of carbohydrate shapes how quickly flocs form, how efficiently nutrients are assimilated, and how stable the microbial community remains. Despite the technology’s successful adoption across broodstock, nursery, and grow-out phases of shrimp production, information on its effectiveness during the delicate larval and postlarval stages of Penaeus vannamei has remained scarce—precisely the gap the Indian team set out to fill.

The experiment took place at the BKMN shrimp hatchery in Undavalli, in the Guntur district of Andhra Pradesh. The researchers used eight circular high-density polyethylene tanks of 1000 liters capacity, each with a working volume of 800 liters, meticulously cleaned and treated with bleaching powder before use. Specific pathogen-free shrimp nauplii, confirmed disease-free by PCR testing, were stocked at an extraordinarily high density of 100 larvae per liter—80,000 animals per tank—at the mysis-1 stage. Three biofloc treatments were established at a fixed carbon-to-nitrogen ratio of 15:1, using fructose, lactose, or dextrose as the carbon source, alongside a control with no carbohydrate addition. The trial ran for 13 days, until the larvae reached postlarval stage 10, with zero water exchange throughout.

Building the flocs required careful staging. Following the protocol pioneered by aquaculture researcher Yoram Avnimelech, the team introduced nitrogen on the first day by adding 1.5 grams of ammonium chloride, then added carbon sources on days three and five at 5.62 grams, doubling the dose to 11.25 grams on day seven. The water’s transformation from clear and transparent to light brown signaled that floc formation was underway. Larvae were fed a commercial microencapsulated diet with a minimum protein content of 52 percent, distributed across six daily feedings, with quantities adjusted to floc volume at each developmental stage.

The water chemistry results told a clear story. Temperature remained in the optimal 27 to 29 degrees Celsius range, and dissolved oxygen stayed between 5.30 and 6.24 milligrams per liter, comfortably above the lethal threshold of 1.0 ppm reported for the species. More striking were the differences in nitrogen compounds. Total ammonia nitrogen in the biofloc tanks ranged from 0.69 to 0.78 milligrams per liter, significantly lower than the control’s 1.07. Un-ionized ammonia, which is highly toxic to shrimp, measured just 0.12 milligrams per liter in the biofloc treatments against 0.36 in the control. Nitrite, which damages the circulatory and immune systems of aquatic animals, was a mere 0.06 milligrams per liter in the biofloc systems compared with 1.53 in the control—well above the 1.0 milligram per liter considered optimal for successful culture. Nitrate and alkalinity also differed significantly among treatments, with biofloc alkalinity of roughly 127 to 128 milligrams per liter far exceeding the control’s 91.38.

Survival data sealed the case for dextrose. At postlarval stage 1, dextrose-fed tanks achieved 93 percent survival, followed by fructose at 88.67 percent, lactose at 86.33 percent, and the control at 79.33 percent. By postlarval stages 5 and 10, the gap widened: 90.67 percent for dextrose, 85.67 percent for fructose, 78.33 percent for lactose, and a sobering 66.67 percent for the control. The researchers attribute dextrose’s advantage to its chemistry. As a monosaccharide derived from simple starch, it is readily broken down by bacteria, driving robust floc formation—the dextrose treatment produced the greatest floc volume at 1.62 milliliters per liter, compared with 1.12 for fructose and just 0.84 for lactose, a disaccharide that microbes decompose more slowly.

The broader implications extend beyond a single hatchery in coastal India. Every biofloc treatment group surpassed the 70 percent survival benchmark considered appropriate for the species and for experimental hatcheries, and the overall biofloc survival range of 71 to 86 percent dwarfed the control’s 53 percent. Because the systems operated with zero water exchange, they promise reduced water costs, enhanced biosecurity against pathogens, and a smaller environmental footprint—attributes that matter enormously as the industry confronts disease outbreaks and tightening environmental regulations. The flocs themselves add nutritional value, offering shrimp a supplementary microbial food source alongside formulated feeds.

For an industry that contributes roughly 1.24 percent to India’s gross value added and more than 7.28 percent to agricultural GVA, with exports of 12.22 million tonnes valued at 1.42 billion US dollars in 2023, even incremental gains in hatchery survival compound into substantial economic returns. The study’s conclusion is pragmatic: fertilization with dextrose at a 15:1 carbon-to-nitrogen ratio can efficiently maintain a shrimp hatchery system without any water exchange. As biofloc technology continues its march from experimental tanks to commercial operations worldwide, this finding suggests that one of the most consequential decisions a hatchery manager makes may be as simple as choosing the right sugar.

Subject of Research: Biofloc technology with different carbon sources for Pacific white shrimp hatchery production

Article Title: Hatchery performance of Pacific white shrimp, Penaeus vannamei in Biofloc technology by using different carbon sources

Article References: Suneetha, K., Padmavathi, P., & Chatla, D. (2024). Hatchery performance of Pacific white shrimp, Penaeus vannamei in Biofloc technology by using different carbon sources. Blue Biotechnology, 1(1), Article 13. https://doi.org/10.1186/s44315-024-00016-4

Image Credits: AI Generated

DOI: 10.1186/s44315-024-00016-4

Keywords: biofloc technology, Pacific white shrimp, Penaeus vannamei, aquaculture, dextrose, carbon source, water quality, larval survival, hatchery, zero water exchange, carbon-nitrogen ratio, sustainable aquaculture