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

The giant river prawn is a culinary staple across South and Southeast Asia, supporting millions of livelihoods from Bangladesh to Vietnam. Although the species naturally lives in freshwater, berried females migrate to brackish water to spawn, and the larvae pass through eleven developmental stages before becoming postlarvae. Hatcheries typically rear these postlarvae in brackish water at salinities of around 10 to 12 parts per thousand before they migrate back toward freshwater. This nursery phase is a critical bottleneck: postlarvae are small, fragile, and highly sensitive to water quality, so any management tool that improves survival at this stage carries enormous economic weight.

Biofloc technology works by adding a carbon source, in this case maize starch, to culture water at a controlled carbon-to-nitrogen ratio. This fuels heterotrophic bacteria that convert toxic nitrogenous wastes such as ammonia into microbial biomass. The resulting flocs, aggregates of bacteria, algae, protozoa, organic particles and microscopic animals, are then grazed by the cultured animals, supplementing their formulated feed. The system recycles waste into food, reduces water exchange, and has been hailed as an environmentally friendly component of the so-called blue revolution. But the technology has a dark side: when floc volume climbs too high, the suspended solids can clog delicate gills, depress dissolved oxygen, block light penetration, and ultimately stunt growth or kill the animals outright.

Previous work had hinted at these dangers. In pink shrimp Farfantepenaeus duorarum, floc volumes reaching 17 milliliters per liter were associated with mortality from gill clogging. Researchers studying whiteleg shrimp found that low and medium total suspended solids levels improved water quality and performance, while high solids levels reduced productivity and survival. Yet for the giant river prawn, one of Asia’s most important aquaculture commodities, no published study had systematically tested how different floc volumes affect water quality, microbial communities, zooplankton abundance, growth, survival, body composition and profitability during the nursery phase. The new study set out to fill exactly that gap.

The experiment was elegantly simple in design. Over four weeks, the team reared giant river prawn postlarvae, each starting at an average weight of just 21.8 milligrams, in twelve 125-liter tanks holding 100 liters of brackish water at 15 parts per thousand salinity. Each tank was stocked with 500 postlarvae at a density of five individuals per liter. The tanks were assigned to four treatments in triplicate: three biofloc volume levels maintained by periodic solids removal, at 2 to 5, 7 to 10, and 12 to 15 milliliters per liter, and a zero-exchange biofloc system in which no solids were ever removed, allowing floc volume to climb unchecked. Floc volume was measured daily using Imhoff cones, and precise equations guided how much water should be drained and replaced to hold each target level.

The water chemistry results revealed a system under strain in the zero-exchange treatment. Temperature, pH, nitrite and nitrate remained statistically similar across all four groups, but dissolved oxygen dropped significantly in the zero-exchange tanks by weeks three and four, likely because the accumulating microbial and zooplankton biomass drove up biological oxygen demand. Total suspended solids and floc volume rose steadily in the zero-exchange system, while the managed treatments stayed within ranges considered safe for prawn and shrimp culture. Ammonia was briefly higher in the lowest floc volume group during the first week but fell within safe limits and declined thereafter, suggesting that nitrifying bacteria were functioning effectively in all systems.

The microbial story proved equally revealing. Sixteen genera of zooplankton were identified across the tanks, including six genera of ciliates, nine of rotifers and one of nematodes. Ciliates, rotifers and nematodes were all significantly more abundant in the zero-exchange system, apparently because zooplankton assemblages require suspended solids as substrate. But abundance of these live foods did not translate into better prawn performance. More importantly, the density of Vibrio species, bacteria widely regarded as a serious nuisance in prawn hatcheries, was significantly lower in the 2 to 5 milliliter per liter treatment than in the 12 to 15 and zero-exchange groups. Meanwhile, Lactobacillus species, considered beneficial for gut health and water quality, were significantly more abundant in all three solids-removal treatments than in the zero-exchange system, a microbial shift the authors interpret as evidence of a healthier culture environment.

When it came to the prawns themselves, growth told a surprisingly flat story: final weight, weight gain and specific growth rate were statistically indistinguishable across all four treatments, indicating that the animals could grow at similar rates regardless of floc management. Survival, however, was a different matter. The 2 to 5 milliliter per liter treatment produced significantly higher survival, reaching 82.33 percent, along with the best feed conversion ratio of 1.52, compared with a dismal 8.63 in the zero-exchange system. The feed conversion ratios in the three managed treatments, at 1.52, 1.60 and 2.07, also compared favorably with values reported previously for prawn culture in biofloc systems. Because survival and feed efficiency drive nursery economics, the lowest floc volume group delivered significantly higher gross returns, net returns and benefit-cost ratios than the other treatments.

Proximate analysis added a nutritional dimension to the findings. The whole-body dry matter, protein, lipid, ash and carbohydrate content of the postlarvae did not differ significantly among treatments, suggesting that floc volume did not alter the prawns’ fundamental nutritional profile. The bioflocs themselves showed similar protein and lipid content across groups, though ash was higher in the 12 to 15 and zero-exchange treatments and carbohydrate was higher in the two lowest floc volume groups. The authors note that the relatively low lipid content of the postlarvae likely reflects young animals channeling energy into growth rather than storage, and that the protein levels observed are consistent with those of postlarvae fed premium live foods such as adult Artemia, Tubifex worms and Moina.

The practical message for hatchery operators is strikingly clear. Maintaining floc volume at 2 to 5 milliliters per liter, corresponding to a total suspended solids level of roughly 294 milligrams per liter, through periodic solids removal produced the highest survival, the best feed conversion, a healthier microbial balance with fewer Vibrio and more Lactobacillus, and the strongest economic returns. The authors recommend that commercial prawn nurseries using biofloc systems adopt routine solids removal as a core management strategy. They also caution that their study did not characterize the full bacterial diversity, virulent Vibrio strains or probiotic candidates within the flocs, and they call for future research into bacterial community dynamics, amino acid and fatty acid profiles, and immune gene expression in prawns reared across different floc management regimes. For an industry seeking to grow more food with less water and fewer chemicals, this study offers a deceptively simple prescription: in the microbial economy of the biofloc pond, moderation pays.

Subject of Research: Optimizing biofloc volume for giant river prawn postlarvae nursery culture in brackish water biofloc systems

Article Title: Effect of biofloc volume on growth, survival, economics and proximate composition of Macrobrachium rosenbergii postlarvae cultured in brackish water biofloc system

Article References: Hosain, M. E., Amin, S. M. N., Karim, M., Arshad, A., Kamarudin, M. S., Shohaimi, S., Naser, M. N., & Brown, C. L. (2025). Effect of biofloc volume on growth, survival, economics and proximate composition of Macrobrachium rosenbergii postlarvae cultured in brackish water biofloc system. Blue Biotechnology, 2(1), Article 4. https://doi.org/10.1186/s44315-025-00030-0

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00030-0

Keywords: biofloc technology, Macrobrachium rosenbergii, giant river prawn, aquaculture, postlarvae, nursery phase, water quality, Vibrio, Lactobacillus, survival, feed conversion ratio, sustainable aquaculture

Biofloc technology, commonly abbreviated as BFT, is essentially a recirculating system built around microbes rather than mechanical filtration. The tanks hold a dense, suspended community of microalgae, autotrophic and heterotrophic bacteria, fungi, ciliates, protozoans, and small zooplankton such as rotifers, copepods, and nematodes, all maintained with minimal or zero water exchange. The central trick is the manipulation of the carbon-to-nitrogen ratio. Fish excrete nitrogenous waste, chiefly ammonia, which is toxic at even modest concentrations. By adding an external carbon source such as molasses, sugar, glucose, wheat flour, or regional agricultural by-products, farmers push the ratio high enough that heterotrophic bacteria dominate. These bacteria assimilate inorganic nitrogen directly into their own cell biomass, converting a pollutant into living feed. The resulting aggregates, the flocs themselves, remain suspended in the water column and are grazed by the cultured animals.

The nutritional payoff is substantial. According to the review, biofloc typically contains 12 to 50 percent protein, 0.5 to 41 percent lipids, 14 to 59 percent carbohydrates, and 3 to 61 percent ash on a dry-weight basis, with the exact profile depending on the carbon source, salinity, and species cultured. Marine bioflocs are especially rich in essential amino acids including valine, lysine, leucine, phenylalanine, and threonine, although they can be deficient in vitamin C, arginine, methionine, and cysteine. Beyond macronutrients, flocs deliver bioactive compounds such as essential fatty acids, carotenoids, chlorophylls, free amino acids, and trace minerals, which support cell membrane integrity, antioxidant defenses, reproduction, and immune function. Researchers cited in the review note that biofloc is a valuable protein source not only for tilapia and prawns but also for mussels, and studies have shown that shrimp raised in biofloc systems accumulate more nitrogen in their biomass than those in conventional cultures.

The consequences for feed economics are significant, because feed is the single largest cost in most aquaculture operations. By recycling organic waste into in-situ microbial protein, BFT reduces dependence on expensive commercial feeds, and the review reports lower feed conversion ratios and higher protein efficiency ratios across numerous trials. In one experiment on Nile tilapia, daily addition of molasses as a fresh carbon source increased growth rates and productivity while cutting costs by 15 percent and raising profitability by 25 percent. Feeding strategy matters too: tilapia fed twice daily under biofloc conditions achieved 100 percent survivability and production of 11.27 kilograms per cubic meter, while reducing labor costs. Because the system also slashes water exchange, it conserves two of aquaculture’s scarcest resources, water and land, making high-density culture feasible for small-scale and resource-limited farmers.

Getting the carbon-to-nitrogen ratio right, however, is a delicate balancing act, and much of the recent literature reviewed by the authors focuses on finding species-specific optima. In stinging catfish, researchers tested ratios of 12, 15, 18, and 21 and found that a ratio of 15 produced the highest protein content and lowest moisture in the fish, with no significant differences in lipid and ash among the higher treatments. In common carp, sugarcane molasses raised the ratio and stimulated bioflocculation and heterotrophic bacterial growth, with a ratio of 19:1 improving water quality and growth, but pushing to 23:1 worsened feed conversion, protein efficiency, and feed intake. Ratios above 20:1 led to accumulation of dissolved salts and settled biomass that destabilized the system. In common carp fed at ratios of 10:1, 15:1, and 20:1, the highest ratio proved optimal for physiological and immune responses as well as growth, underscoring that the ideal value shifts with species, carbon source, and culture conditions.

Water quality dynamics explain why these thresholds matter. As carbon input rises, heterotrophic bacteria proliferate, and the resulting bacterial biomass, aggregated organic matter, and floc particles drive total suspended solids upward. Mineralization of that organic matter releases dissolved ions, raising total dissolved solids as well. Meanwhile, pH, total ammonia nitrogen, and nitrite nitrogen tend to fall as the ratio increases, because bacteria assimilate the nitrogen before it becomes toxic. In trials with Nile tilapia in cement ponds, both sugarcane molasses and wheat flour significantly lowered pH, unionized ammonia, and nitrite compared with controls, while nitrate and suspended solids climbed. Elevated nitrogenous compounds can inhibit nitrification and degrade water quality, so operators must monitor solids and be prepared to remove excess floc, often through settling basins or filtration.

One of the most striking findings synthesized in the review is the immune boost that biofloc microbes appear to provide. Specific microorganisms in the floc community function as natural probiotics, and fish and shellfish raised in these systems show significantly higher phagocytosis rates, nitroblue tetrazolium and myeloperoxidase activity, alternative complement pathway activity, total immunoglobulin levels, lysozyme activity, and antioxidant enzymes such as superoxide dismutase and catalase compared with animals in conventional systems. The practical result is greater resistance to major pathogens including Aeromonas hydrophila, Vibrio harveyi, Streptococcus agalactiae, and Edwardsiella tarda. Hematological studies reinforce the picture: genetically improved farmed tilapia in biofloc systems showed elevated serum glutathione peroxidase and lysozyme activity, common carp given cane molasses showed markedly reduced stress, and tilapia reared with zero water exchange displayed increased red blood cell counts and hemoglobin alongside reduced cortisol, liver enzymes, and urea, indicating improved welfare and homeostasis.

The microbial ecology underpinning these benefits is complex and still being mapped. Floc-forming microbes secrete extracellular polymeric substances that glue particles together and stabilize the aggregates, while nitrifying bacteria handle chemoautotrophic oxidation of ammonia, and grazers such as rotifers and protozoans recycle nutrients and enrich the floc as a food source. Systems are typically classified as green water biofloc, exposed to natural light and driven by both algal and bacterial processes, or brown water biofloc, run in closed environments where bacteria alone regulate water chemistry. Community composition shifts with the carbon source, salinity, and cultured species, and phytoplankton contribute by absorbing excess nutrients and producing dissolved oxygen. Managing this living suspension, rather than sterilizing it, is the fundamental philosophical shift that distinguishes biofloc from conventional intensive culture.

The technology is not without drawbacks, and the review is candid about them. Continuous, vigorous aeration is required to satisfy the biological oxygen demand of both animals and microbes, driving up energy consumption and operational costs. High water temperatures can favor pathogenic microbial growth, and accumulated organic load degrades water quality if solids management lapses. Consumer acceptance of fish raised in microbial floc also remains an open question that the authors say must be addressed ethically and transparently. Current applications concentrate on herbivorous, detritivorous, and bottom-dwelling species such as tilapia and shrimp; extending the approach to carnivorous fish will require redesigned carbon dosing and system architecture. The authors recommend optimizing biofloc concentrations, compartmentalizing system components for better control, and investing in farmer training and financial support to widen adoption.

Even with those caveats, the trajectory is clear. Biofloc technology aligns economic self-interest with environmental stewardship, turning the aquaculture industry’s most stubborn waste problem into a protein asset while cutting water use, land requirements, and antibiotic dependence. For policymakers and investors seeking responsible aquaculture growth, and for smallholder farmers in water-scarce regions who cannot afford conventional recirculating systems, the review positions biofloc as a practical bridge between rising global fish demand and the ecological limits of the planet, provided that research continues to refine carbon management, microbial community control, and species-specific system design.

Subject of Research: Biofloc technology for sustainable aquaculture: nutrition, water quality, and system efficiency

Article Title: The role of biofloc technology in sustainable aquaculture: nutritional insights and system efficiency

Article References: Yadav, N. K., Paul, S., Patel, A. B., Mahanand, S. S., Biswas, P., Choudhury, T. G., Baidya, S., & Meena, D. K. (2025). The role of biofloc technology in sustainable aquaculture: nutritional insights and system efficiency. Blue Biotechnology, 2(1), Article 7. https://doi.org/10.1186/s44315-025-00025-x

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00025-x

Keywords: biofloc technology, aquaculture, sustainability, carbon-nitrogen ratio, water quality, fish nutrition, tilapia, shrimp farming, microbial protein, feed conversion ratio, fish immunity, wastewater recycling

The stakes are considerable. Shrimp aquaculture supplies more than half of the global shrimp market, and L. vannamei alone accounts for roughly 80 percent of farmed shrimp output, thanks to its rapid growth and tolerance of salinities ranging from 0.5 to 40 parts per thousand. But the industry is chronically undermined by environmental stress. Rising ammonia in culture water impairs growth, invites disease, and kills animals; temperature swings disrupt hormones and enzymes, which function best between 28 and 32 degrees Celsius; and ammonia competes with oxygen for binding sites on the oxygen-carrying pigment haemocyanin, choking respiration and suppressing immunity. Biofloc technology promises a way out by converting toxic nitrogenous waste into microbial biomass that shrimp can themselves consume.

To understand what biofloc actually does inside the animal, the team first ran an optimization experiment using a Taguchi L9 orthogonal array and grey relational analysis, testing stocking densities of 100 to 300 shrimp per cubic meter, carbon-to-nitrogen ratios of 10 to 20, and probiotic doses of 7 to 21 milliliters per liter. Two winning configurations emerged as treatments for the main trial: GRG1, with 200 shrimp per cubic meter, a C/N ratio of 10:1, and 14 milliliters per liter of the probiotic Bacillus tropicus; and GRG2, with the same density but a C/N ratio of 20:1 and half the probiotic dose. Both were run inside the IMTAS facility, a closed-loop system combining shrimp culture, cyclone-based flocculation with UV treatment, and a phytoremediation unit where Caulerpa seaweed strips nutrients from recirculating water, all monitored through an Internet of Things control network.

The water chemistry alone told a compelling story. Over the twelve-week culture period, both biofloc treatments maintained significantly lower total ammonia nitrogen, nitrite, and phosphate than the control, which relied on a modest 2.5 percent daily water exchange and no microbial management. Dissolved oxygen was significantly higher in the biofloc tanks, as were pH levels, while conductivity, total dissolved solids, and salinity were all lower. In other words, the microbial flocs were doing precisely what biofloc advocates claim: assimilating inorganic nitrogen into microbial biomass and stabilizing the culture environment without external water input.

The shrimp responded in kind. Mean final weight climbed from 10.50 grams in the control to 21.45 grams in GRG1, more than a doubling. Specific growth rate rose from 3.96 to 4.79 percent per day, feed conversion ratio improved from 1.39 to 1.05, and survival jumped from 49.08 percent to 75.91 percent. GRG1 outperformed every other treatment on every metric measured, a phenotypic signal that the transcriptomic data would soon help explain.

For the molecular analysis, the researchers dissected midgut tissue at harvest, flash-froze it in liquid nitrogen, and sequenced RNA on an Illumina NovaSeq 6000, mapping 150-base-pair paired-end reads against the L. vannamei reference genome. Differential expression analysis with DESeq2, using strict thresholds of a log2 fold change of at least 1 and an adjusted p-value of 0.05 or below, revealed 1,245 differentially expressed genes in GRG1 versus the control, 1,145 in GRG2 versus the control, and 681 between the two biofloc treatments themselves. Hierarchical clustering and principal component analysis confirmed that both biofloc groups clustered apart from the control, with treatment-specific expression signatures. The smaller number of differences between GRG1 and GRG2 makes sense: both animals were living in biofloc, so their shared transcriptomic response dwarfed the differences between the two floc recipes.

The pathway-level results were the most revealing. In GRG1 versus the control, three KEGG pathways were significantly enriched: the proteasome, autophagy, and phagosome pathways. Proteasome subunits across both the 26S regulatory particles and the 20S core were strongly upregulated, indicating accelerated degradation of ubiquitinated and misfolded proteins and tighter cellular quality control. The autophagy pathway showed four-fold or greater upregulation of TSC1, AMPK, ULK1/2, LC3, ATG2, and ATG9L, pointing to vigorous autophagosome formation and cellular component recycling, while BNIP3, a hypoxia-responsive gene, rose 3.2-fold, suggesting improved tolerance of environmental stress. In the phagosome pathway, tubulin genes surged up to ten-fold, actin and integrins rose five-fold, and thrombospondin increased a remarkable 22-fold, together implying enhanced cytoskeletal dynamics, immune cell adhesion, and intracellular pathogen clearance.

GRG2 shrimp told a different molecular story. Their enriched pathways were aminoacyl-tRNA biosynthesis and protein processing in the endoplasmic reticulum, reflecting a shift in how protein was built rather than broken down. Alanyl-tRNA synthetase was upregulated, favoring alanine incorporation, while synthetases for glutamine, aspartate, and glycine were downregulated, hinting at selective modulation of amino acid use under the higher carbon-to-nitrogen regime. In the endoplasmic reticulum pathway, heat shock protein 70 rose four-fold and ER-associated degradation genes such as p97 and ufd1 climbed, while calnexin, BiP, and eIF2α fell, suggesting a reduced burden from the unfolded protein response. Comparing the two biofloc treatments directly, oxidative phosphorylation emerged as the distinguishing pathway: NADH dehydrogenase subunits were upregulated in GRG1, while cytochrome c oxidase subunits were downregulated, indicating treatment-specific differences in mitochondrial energy metabolism.

The convergence of molecular and phenotypic data is what gives the study its punch. GRG1, the treatment with the cleanest water and the strongest growth, was also the one with the greatest enrichment of protein turnover, immune, and energy pathways, suggesting that biofloc conditions triggered a systemic reprogramming that favored metabolic efficiency and resilience. Proteasome activity kept cellular proteins in order, autophagy recycled components under culture stress, and phagosome activation plausibly bolstered defense against pathogens, all of which created an internal environment conducive to the doubled weight gain and 76 percent survival observed. The authors are careful to frame the work as exploratory: the control group had only two usable RNA libraries after one degraded, physiological immune markers such as total hemocyte count and phenoloxidase activity were not measured, and the control’s different water exchange regime makes it hard to fully separate biofloc effects from water management effects. No qPCR validation was performed, so the expression patterns await independent confirmation.

Even with those caveats, the study delivers something the biofloc field has lacked: a tissue-specific, genome-wide account of what microbial flocs actually do to the animals farmed among them. With the sequencing data deposited in the NCBI Sequence Read Archive under BioProject PRJNA1468551, the researchers have laid a molecular foundation for optimizing biofloc protocols, potentially identifying gene expression markers that predict which floc configurations will produce the healthiest, fastest-growing shrimp. As global demand for shrimp keeps climbing and freshwater and coastal resources come under pressure, farming systems that let microbes do the water treatment, while the shrimp’s own genes do the rest, may prove to be one of aquaculture’s most important technological turns.

Subject of Research: Transcriptomic responses of Pacific white shrimp to biofloc technology in indoor aquaculture

Article Title: Transcriptomic adaptation of Litopenaeus vannamei to biofloc conditions in an indoor aquaculture system

Article References: Transcriptomic adaptation of Litopenaeus vannamei to biofloc conditions in an indoor aquaculture system. (n.d.). https://doi.org/10.1007/s44338-026-00257-0

Image Credits: AI Generated

DOI: 10.1007/s44338-026-00257-0

Keywords: biofloc technology, Litopenaeus vannamei, transcriptomics, aquaculture, gene expression, RNA sequencing, immune response, protein turnover, autophagy, phagosome, oxidative phosphorylation, water quality