Sustainable Aquaculture Practices Research Articles

Evaluation of the probiotic potential of Streptomyces antibioticus and Bacillus cereus on growth performance of freshwater catfish Heteropneustes fossilis

Application of probiotics in aquaculture helps to improve the survivability, growth and immunity of aquatic organism in sustainable aquaculture practices. This study was conducted to evaluate the probiotic potentiality of Streptomyces antibioticus EW1 and Bacillus cereus EW5 isolated from the digestive tract of earthworm (Eisenia fetida) and also determine their effects as probiotic in juvenile catfish (Heteropneustes fossilis). The bio safety assay confirmed that the isolates were not pathogenic to the host fish. These strains were able to survive in acidic as well as alkaline conditions, higher tolerance to bile salt as well as gastric juice and high surface hydrophobicity to solvents and displayed extracellular enzyme activity and moreover susceptibility to various antibiotics. Their antimicrobial activity was assessed against two fish pathogens: Aeromonas veronii (MN602971) and Stenotrophomonas maltophilia (MN602972). Among two isolates, the EW1 confirmed good antimicrobial activity against fish pathogens. The isolated bacterial strains were identified and established on the basis of their colony morphology, biochemical characteristics and 16S rRNA sequencing which revealed that the isolates exhibited 99 % sequence homology with Streptomyces antibioticus EW1 (MH301104) and Bacillus cereus EW5 (MH301102). A 45-day feeding trial was conducted to examine the effect of probiotic inoculated fish diet for the freshwater catfish Heteropneustes fossilis. Among three isonitrogenous (30 % CP) diets: RD (reference diet), T1 (diet with Streptomyces antibioticus) and T2 (diet with Bacillus cereus), fish fed T1 diet showed significantly higher growth, digestibility and higher values of crude protein and lipid than fishes reared with T2 and RD. The result of present study suggest that diet supplemented with Streptomyces antibioticus (T1) can be perform as safe probiotic and alternative protein source in the formulation of diet for H. fossilis.

Aquaculture, Fish and Fisheries: A new home for the Blue Revolution

<i>Aquaculture, Fish and Fisheries</i>: A new home for the Blue Revolution

Empowering Fish-Farmer through Coastal Field School: Towards Sustainable Aquaculture Practice

Central Java Province is among the largest aquaculture producers in Indonesia. This hefty contribution also comes with a challenge of degraded coastal areas primarily due to mangrove conversion into ponds, land subsidence, and raising sea surface. In Demak Regency, abrasion and robs flood have adversely affected the farmers’ aquaculture ponds since the past decades. The changing coastal environment and lack of knowledge to adapt in aquaculture management led to declining production that hampered the community’s resilience in the future. To help the farmers to thrive, an initiative called Coastal Field School (CFS) was implemented in 10 villages in Demak. Principally, CFS is a participatory learning method that emphasizes problem solving and discovery based on learning toward their production systems. The entire CFS program took place in 2015 – 2020, however this study only focused on the CFS conducted in Bedono village during May 2019 – September 2019. This paper discusses the CFS impact on the farmers’ knowledge change using the indicators of farmers’ program participation level, pre-test and post-test result to determine the knowledge improvement, aquaculture management technique, and productivity rate. The test was analyzed using a paired t-test where the knowledge level of farmers increased significantly (p < 0.001). The farming productivity rate also improved by nearly 30%. It is concluded that CFS can strengthen the farmers’ resilience in the degraded coastal area in Demak.

The institutional dimension on the fish farming activity in the Amacuzac basin: looking for ways to stem the loss of wetlands in central Mexico

ABSTRACT The State of Morelos is a pioneer and the leading producer of ornamental and edible fish in Mexico. In 2010, the State invested in increasing production units by improving infrastructure and the genetic quality of breeding stocks, as well as introducing non-native species. We investigated the current situation of aquaculture in the Amacuzac river basin in Morelos and the actors involved in this activity, their power relationships and their field of action in order to identify alternative ways of sustainable production. Information provided by government agencies showed significant inconsistencies in records, control and location of farms. Fish producers interviewed showed various management anomalies regarding water use and the prevention of fish escape and disease. Immediate joint efforts by state authorities and the aquaculture sector are needed to halt the ecological impact on wetlands and rivers and to implement environmentally and economically sustainable aquaculture practices in Morelos.

Fish out of water: consumers\u2019 unfamiliarity with the appearance of commercial fish species

Seafood labels play an increasingly key role in assisting consumers in purchasing processed and featureless fish products, and in encouraging sustainable fishing and aquaculture practices. While informed purchasing choices are typically influenced by traceability and labelling awareness, they also depend on the consumers’ ability to identify and discriminate the fish species available on the market, which to date remains notably unexplored. We asked 720 people across six European countries to identify pictures of six fish species commonly sold in Europe. We reveal that European consumers have a poor understanding of the appearance of the fish they consume (overall ∼ 30% correct identification), with British consumers performing the poorest and Spanish ones doing best. We noted cultural association with some species, whereby the most regionally consumed fish are more easily recognized. We argue that despite recent improvements in technological solutions, stakeholder dialogue, and policy implementation, seafood market transparency will remain open to malpractice until consumers restore connection with their food.

Design of Submerged Fixed Bed Filter for High Density Shrimp Culture in Recirculating Aquaculture System

Shrimp is Indonesia’s the leading export commodities from Indonesia, but in recent years the shrimp industry has been threatened by disease outbreaks due to environmental quality decline. To overcome these challenges, there is a need for a cultivation technology which provides opportunities for intensive shrimp culture in a narrow area, resulting high productivity and having less environmental impact. Recirculating aquaculture systems (RAS) was the best option to provide high density shrimp culture without leading to environmental damage due the system equiped with water treatment unit. This study aimed to design a submerged filter which can be used in commercially recirculating systems for high density shrimp culture. Submerged filter as water treatment unit for ammonia conversion, it was designed based on organic load mass balance derived from feeding regimes. A RAS with 8 m3 volume capacity use for rearing 400 shrimps m−3, has dissolved oxygen levels range between 6-7 mg L−1, nitrification rate 0.45 g TAN m−2day−1 and TAN levels <1.8 mg L−1, based on spreadsheet calculation will require submerged filter media with 0.07 m3 in volume, media depth 0.3 m, and filter media specific surface area 1200 m2 m−3. Submerged filter design for high density shrimp culture in a narrow place must have a compact design. It can be achieved by selecting filter media type with large specific surface area values. Filter media with a large specific surface area makes biofilter design has smaller dimensions. Submerged filter as water treatment unit in recirculating system for high density shrimp culture will reduce TAN level in water. Waste water in this system is reuse for shrimp culture, no waste water disposal to the environment which leading to sustainable aquaculture practice.

Investigations on the use of exopolysaccharide derived from mycelial extract of Ganoderma lucidum as functional feed ingredient for aquaculture-farmed red hybrid Tilapia (Oreochromis sp.)

There is growing interest in medicinal fungi for promoting immunomodulation benefits in humans and animals. In this study, exopolysaccharide (EPS) from Ganoderma lucidum was used in feed (EFF) on production of farmed-red hybrid Tilapia performance for sustainable aquaculture. The feeding trial was conducted for a period of 42 days. Tilapia weight gain (WG) was significantly the highest (18.75 ± 0.03 g/fish) using 3 g/kg of EFF compared to control (0 g/kg EFF; 12.4 g/fish). Fish fed with 3 g/kg of EFF were shown to be healthiest as attested by measured organosomatic indices that achieved an hepatosomatic index (HSI) of 2.22% and condition factor (CF) of 1.46% compared to control (1.97% HSI; 1.60 CF). Antioxidant activity of Glutathione S-transferase (GST) exhibited significantly lower activities in 1 and 2 g/kg of EFF while increasing catalase (CAT) activity was detected in higher EFF (2-3 g/kg of EPS). Muscle compositions were not affected by the EFF feeding regimes. In contrast, EFF feeding produced significantly higher haemoglobin (7.43 g/dl), haematocrit (37.5%), red blood cell (2.69 106/mm3), and white blood cell (176.7 106/mm3) compared to control group. In summary, EFF was beneficial in promoting growth, stimulating antioxidant enzymes, and health status of red hybrid Tilapia, which highlights the potential for future use in intensive sustainable aquaculture practices.

Antiparasitic and Antibacterial Functionality of Essential Oils: An Alternative Approach for Sustainable Aquaculture.

Using synthetic antibiotics/chemicals for infectious bacterial pathogens and parasitic disease control causes beneficial microbial killing, produces multi-drug resistant pathogens, and residual antibiotic impacts in humans are the major threats to aquaculture sustainability. Applications of herbal products to combat microbial and parasitic diseases are considered as alternative approaches for sustainable aquaculture. Essential oils (EOs) are the secondary metabolites of medicinal plants that possess bioactive compounds like terpens, terpenoids, phenylpropenes, and isothiocyanates with synergistic relationship among these compounds. The hydrophobic compounds of EOs can penetrate the bacterial and parasitic cells and cause cell deformities and organelles dysfunctions. Dietary supplementation of EOs also modulate growth, immunity, and infectious disease resistance in aquatic organisms. Published research reports also demonstrated EOs effectiveness against Ichthyophthirius multifiliis, Gyrodactylus sp., Euclinostomum heterostomum, and other parasites both in vivo and in vitro. Moreover, different infectious fish pathogenic bacteria like Aeromonas salmonicida, Vibrio harveyi, and Streptococcus agalactiae destruction was confirmed by plant originated EOs. However, no research was conducted to confirm the mechanism of action or pathway identification of EOs to combat aquatic parasites and disease-causing microbes. This review aims to explore the effectiveness of EOs against fish parasites and pathogenic bacteria as an environment-friendly phytotherapeutic in the aquaculture industry. Moreover, research gaps and future approaches to use EOs for sustainable aquaculture practice are also postulated.

Consumption of monogenean eggs by crustaceans and fish

The use of biological agents to control parasitic diseases in aquaculture is becoming increasingly popular as it is considered safe, effective and economically beneficial strategy for sustainable aquaculture practices. Monogeneans are among the most problematic parasites in fish farms. Their local outbreaks are largely attributed to the accumulation of eggs on farming structures, and the removal of these eggs by biological agents can be a novel solution to control monogenean diseases. We assessed the consumption of monogenean eggs by two amphipod species (a gammarid and a caprellid), the grass shrimp Palaemon pacificus and three fish (two monacanthids and Girella punctata). The ingestion of Neobenedenia girellae and/or Heteraxine heterocerca eggs was directly or indirectly confirmed in all of the tested organisms. The eggs ingested by the crustaceans lost viability, while those eaten by fish hatched after excretion. Monacanthid filefish consumed N. girellae eggs at the highest rate, up to more than 23,000 eggs individual-1 24 hr-1. A cohabitation of Seriola dumerili with a monacanthid, Rudarius ercodes, showed a lower acquisition of N. girellae than those kept without R. ercodes. The results indicated that these crustaceans and fish can be useful biological agents for removing monogenean eggs from culturing facilities.

Study on floc characteristics and bacterial count from biofloc‐based genetically improved farmed tilapia culture system

The present study endeavoured to investigate the efficacy of biofloc technology (BFT) and clear water system (CWS) on nursery rearing of genetically improved farmed tilapia (GIFT). The study used outdoor lined pond (0.01 ha), in duplicate, to explore the bacterial community in culture water and gut flora of GIFT and floc characteristics of both systems. Each pond was stocked with 5,000 numbers (0.2 ± 0.02 g/fish) of GIFT fry and reared for 30 days. Biofloc, with carbon: nitrogen ratio of 10:1, was developed and maintained using distillery spent wash (DSW) as organic carbon source and provided with intensive aeration. Total heterotrophic bacteria (THB), Vibrio and Bacillus count of culture water and gut samples were significantly (p < .05) differed between BFT and CWS. Floc volume, size, settling velocity, porosity and floc volume index were documented from BFT system. Plankton count was significantly differed (p < .05) between the BFT and CWS. BFT showed pleiotropic beneficial effect on rearing medium and species health through colonization of probiotic heterotrophic bacteria and elimination of pathogenic bacteria in the gut. Novelty of floc characteristics measured in the present study would help to form the base clue for the scientific understanding of biofloc system which paves to promote the BFT as sustainable aquaculture practice.

A Novel Recirculating Aquaculture System for Sustainable Aquaculture: Enabling Wastewater Reuse and Conversion of Waste-to-Immune-Stimulating Fish Feed

Recirculation aquaculture system (RAS) is a unique indoor fish farming method. Yet, the RAS system needs to address challenges such as effective wastewater/waste management, reduction of feed cost, and usage of antibiotics during farming to become a sustainable aquaculture system. Here, we report a novel RAS-polyhydroxybutyrate (PHB) system to overcome these challenges simultaneously. The RAS-PHB enables effective aquaculture wastewater (AW) treatment for reuse while producing and harvesting PHB-rich biomass as a protein-rich, immune-stimulating fish feed without the need for antibiotics. The feasibility of nitrogen recovery from AW for nonsterile cultivation of a salt-tolerant PHB-producing strain (Zobellella denitrificans ZD1) with or without supplementing agro-industrial wastes/wastewaters (e.g., glycerol, cheese whey wastewater, and aquaculture solid waste) was examined. Glycerol-grown Z. denitrificans ZD1 showed high contents of PHB (48%) and proteins (45.5%). High harvest efficiency of PHB-rich Z. denitrificans ZD1 (97%) was achieved by using small amounts of medium-molecular-weight chitosan. A simple economic analysis showed that the production costs were 0.6–0.7 $/kg of fish produced for the RAS-PHB and 1.2–1.6 $/kg for the conventional RAS, suggesting a reduction of 56% of the total cost by using a RAS-PHB. Overall, this proof-of-concept study showed that the RAS-PHB system is promising for future sustainable aquaculture practice.

Availability of aqua drugs and their uses in semi intensive culture farms at Patuakhali district in Bangladesh

A survey was undertaken to examine the accessibility of aqua-drugs and their applications in the semi-intensive aquaculture farms in Patuakhali district. A total of 83 stakeholders were selected and data gathered from aqua-medicine stores, representatives of different pharmaceuticals and semi-intensive aqua-farms owners via questionnaire interviews. PRA tools like focused group discussion, cross-checking, and key informant interviews were also used. Results show that 78% of farmers conduct polyculture and rest executes monoculture. Among the total fish farmer majority, 38% used lime for pond preparation and water quality management and potash used by 44% farmer as a disinfectant. For increasing dissolve-oxygen Oxy-rich (26%) was vastly used while 28% of farmers don’t use any oxygen supplier in their pond. However, 14% of farmers use commercial Megavit-Aqua growth promoters and 14% farmer used probiotics. For disease control, 52% and 14% of farmers use Renamycin and Renamox respectively due to its easy availability and affordability compared to probiotics. Several issues have been reported due to improper use of aquatic medications, such as lack of information about chemical use, sufficient dosage, form of application and indiscriminate use of antibiotics. This research result will help the policymaker to understand the requirement of fishers for healthy and sustainable aquaculture practices.

Seasonal Variation of Culturable Benthic Soil Prokaryotic Microbiota as Potential Fish Pathogens and Probiotics from an Aquaculture Farm in East Kolkata Wetlands, India

Rising demand in the aquaculture sector tends towards finding innovative ways to promote better yield and profitability. Benthic soil microbiota can provide an insight into the potent opportunistic fish pathogens as well as probiotics present in the aquaculture system. This study reports the seasonal diversity and abundance of fifteen culturable pathogenic bacterial strains belonging to the genera of Comamonas, Aeromonas, Providencia, Klebsiella, Escherichia, Acinetobacter, Serratia, Stenotrophomonas, Staphylococcus, and Enterobacter along with nine probiotic strains native to genera of Bacillus and Pseudomonas isolated from an aquaculture farm benthic soil, located in East Kolkata Wetlands, West Bengal, India. Strains are isolated using traditional microbial culture methods and tested for their antimicrobial susceptibility against commonly available antibiotics. 16S rDNA analysis was done for the identification of the strains and the establishment of their phylogenetic relationships. Among the isolates, B. pumilus strain S8 in the pre-monsoon sample, E. coli strain M2aR1 in the monsoon sample, and A. hydrophila strain P6dF1 in the post-monsoon sample were the most abundant having MPN counts of 275±21 x 106 CFU/gram dry soil, 278±18 x 106 CFU/gram dry soil, and 321±28 x 106 CFU/gram dry soil respectively. Data on the temporal diversity, abundance, and drug-susceptibility of prokaryotic fish-pathogens and probiotics can be used to formulate measures for sustainable aquaculture practices with reduced maintenance costs.

Potential for Sustainable Aquaculture: Insights from Discrete Choice Experiments

The growth in global aquaculture production may address the lack of sustainability in wild fisheries, alleviate poverty in rural and coastal areas, and help meet the worldwide increase in demand for animal protein. However, there is an ongoing debate about the severity of the environmental impact of aquaculture production. Investing in new high-tech production systems can address both productivity growth and the environmental externalities, but high investment costs hinder adoption of high-tech production methods. We investigate the potential of a payment for environmental services program easing access to capital for producers to increase willingness-to-invest in more sustainable aquaculture practices in Vietnam. We conducted two discrete choice experiments to explore the supply and demand side of the policy. First, we elicited the public’s willingness-to-pay to reduce the environmental impact of conventional shrimp aquaculture, and second, we elicited farmers willingness-to-accept a credit subsidy to invest in high-tech production methods. Our results show that the public care about reduced environmental impacts, while farmers strongly prefer increased productivity. Furthermore, the public’s willingness-to-pay for reduced environmental impacts exceeds producer’s willingness-to-accept a subsidy to invest under most scenarios. This implies a potential for more sustainable aquaculture production in Vietnam.

Moving towards more sustainable aquaculture practices: a meta‐analysis on the potential of plant‐enriched diets to improve fish growth, immunity and disease resistance

AbstractAquatic animal diseases are one of the major limiting factors in aquaculture development, with disease emergence forecast to increase with global change. However, in order to treat increasing diseases in a context of global emergence of antimicrobial resistance and strengthening regulations on antimicrobial use, sustainable alternatives are urgently needed. The use of plant supplements to increase fish immunity and disease resistance has gained much popularity within the last decades. The use of functional supplements, such as plants, can also improve growth and feed assimilation, contributing to a better optimization of aquaculture resources (e.g. fish meal inclusion). We conducted a systematic review and meta‐analysis in order to identify the research gaps in the use of plant‐enriched diets in fish aquaculture and estimate, for the first time, the overall efficacy of plant‐enriched diets on fish growth, immunity and disease resistance as well as the effect of intrinsic parameters (fish trophic level, type of plant material, dosage, treatment duration and pathogen species) on the treatment efficacy. We found that plant‐enriched diets significantly enhanced growth, immunity and disease survival of treated fish, regardless of the fish trophic level, treatment duration and type of material used. We also show that plant supplements are a versatile alternative that can benefit different aquaculture sectors (from small‐scale fish farmers to intensive productions). Finally, we observed that studies need to improve the information reported about the plant material used (e.g. origin, identification, chemical composition), in order to allow the comparison of different experiments and improve their repeatability.

Life Cycle Assessment (LCA) Proves that Manila Clam Farming (Ruditapes Philippinarum) is a Fully Sustainable Aquaculture Practice and a Carbon Sink

Manila clam (Ruditapes philippinarum, Adams and Reeve, 1850) farming is a quantitatively important and valuable form of aquaculture production worldwide but, to our best knowledge, no life cycle assessments (LCA) have been undertaken on it. However, being a filter feeder and producing a thick shell during the growing cycle, the capacity of Manila clam to remove nutrients, carbon, nitrogen and phosphorous from the marine environment potentially has some positive effects on the environment. This study was performed in the Sacca di Goro lagoon, located in the southernmost part of the Po River Delta, in the northwestern Adriatic Sea. The LCA of clam farming from a cradle-to-gate perspective have been carried out, including the production stages as seed procuring, sowing, harvesting, depuration and packaging to obtain 1 ton of fresh ready-to-sell clams. The results show that area preparation, fuel combustion and plastic bags were the main contributors to the environmental impacts. The potential capability as a carbon sink of 1 ton of clams has been calculated and the effects on eutrophication reduction by fixing nitrogen and phosphorous in shells, with a net sequestration of 444.55 kg of CO2, 1.54 kg of N and 0.31 kg of P per year.

Chronic stress under commercial aquaculture conditions: Scale cortisol to identify and quantify potential stressors in milkfish (Chanos chanos) mariculture

With the ever increasing demand for food, global aquaculture practices have intensified enormously over the last years. Due to this intensification, (inadequate) management strategies can cause (chronic) stress in cultured fish, hereby affecting fish performance and welfare. In Southeast Asia milkfish (Chanos chanos) is an important aquaculture species. Traditionally, milkfish are cultured in pond systems with extensive culture practices, however, as culture practices intensified, other systems such as marine cages were introduced.Here we aimed to identify potential environmental and/or commercial management related chronic stressors for milkfish kept in marine cage systems using ontogenetic (OG) scale cortisol. We quantified OG scale cortisol as indicator for chronic stress levels in juvenile milkfish (average TL between 20 and 30 cm) from four cage systems (F1-F4; culture time: 2.5–3 months) with different geographic locations and management strategies within the mariculture area (approx. 2.2 × 0.6 km) of the Guiguiwanen Channel in Bolinao (Philippines). The sites were chosen along the mariculture area, with F1 located in the mouth of the channel, F2 at the beginning, F3 mid-way, and F4 at the end of the mariculture area. Each site was sampled twice (I, II) with a time interval of 15 days between both samplings. OG scale cortisol increased significantly between sampling I and II at all four sites, indicating that milkfish at all sites experienced to a certain extent stressful conditions within their cage system. At both samplings OG scale cortisol was highest at F4, where also the highest stocking density was observed. Taking into account the existing culture conditions, OG scale cortisol levels showed that different aspects of typically applied management strategies (e.g. stocking density, feeding strategy) as well as the location might have an effect on the stress level of cultured milkfish and therefore should be considered as potentially severe stressors in milkfish mariculture. To our knowledge this is the first study quantifying OG scale cortisol as indicator for chronic stress in commercial milkfish aquaculture settings, hereby contributing to overall more sustainable aquaculture practices.

Halophyte plants from sustainable marine aquaponics are a valuable source of omega-3 polar lipids

Marine aquaponics is a promising sustainable approach for the production of profitable crops such as halophytes. However, the effect of this culture approach on the lipid composition of halophytes remains unknown. In this work, we contrasted the polar lipidome of Salicornia ramosissima and Halimione portulacoides when produced in marine aquaponics (effluent from a super-intensive flatfish aquaculture production), with that of conspecifics from donor wild populations. Phospholipids and glycolipids were identified and quantified by LC-MS and MS/MS and their profile statistically analysed. Halophytes produced in aquaponics have higher levels of glycolipids with n-3 fatty acids (DGDG 36:3; SQDG 36:3; MGDG 36:6) compared with the donor wild populations. In the case of H. portulacoides, a significant increase of phospholipids bearing n-3 fatty acids (most in PC and PE) was also recorded. These lipids have potential applications in food, feed and pharmaceutical industries, contributing to the valorization of halophytes produced under sustainable aquaculture practices.

Sink or swim? Modernization of mussel farming methods may negatively impact established seabird communities

Marine aquaculture is the fastest growing sector of global food production and is projected to increase to meet future demand. Expansion and modernization of cultivation methods are needed to reach this target but a cost-benefit evaluation for biodiversity conservation is required to achieve sustainable aquaculture practices. We assess drivers of avian richness and abundance in a long-established seabird community present in a series of longline mussel farms in Italy and in response to a recent modernization process in the farming methodology. Over 2 years (24 surveys) we detected a remarkable diversity (15 species in 5 families) and abundance (n = 5858) of birds, of which 40% (n = 6) are regarded as species of international conservation importance. Our models highlighted that the strongest driver explaining variation in abundance and richness across sites was the type of buoy and the associated cultivation method applied. The older and fast-declining double headrope design, offered greater stability for birds to rest. Conversely, the newer and mechanizable single headrope design dominant method in our study site and projected to replace the older system, was unsuitable for birds. Our findings confirm the function of mussel farms as a sort of marine protected area where low anthropogenic disturbance, higher prey availability and suitable artificial structures promote the establishment of seabird communities with minimal impacts on harvest. However, we suggest that potential modernization of farming methods, important to meet future human demand, needs to be carefully assessed and compensated for, particularly where long-established seabird communities have formed in response to such practices.

Macroalgae-enriched diet protects gilthead seabream (Sparus aurata) against erythrocyte population instability and chromosomal damage induced by aqua-medicines

The incorporation of macroalgae on aquafeeds has been suggested to increase fish growth and organoleptic characteristics. Moreover, the potential of macroalgae to strengthen fish capacity to cope with different stressors is a challenging topic in the field of applied phycology. The adverse side effects of aqua-medicines, combined with the hypothesis that a macroalgae-enriched diet can minimize that impact, are the starting point for the present study. Hence, a mix of Ulva rigida, Fucus vesiculosus and Gracilaria gracilis was incorporated (5%) in the gilthead seabream (Sparus aurata) diet, to evaluate a possible protection against the chromosomal damage (measured as erythrocytic nuclear abnormalities) induced by the antibiotic oxytetracycline and the antiparasitic formalin as well as by the model genotoxicant cyclophosphamide. A 60-day differential dietary background was implemented (one fish group fed with standard diet and other with macroalgae-supplemented diet), after which fish were challenged by oxytetracycline, formalin and cyclophosphamide, and appraisals carried out 4 and 18 days later. To shed light on the modulation of the erythrocytic population dynamics, the erythrocyte maturity index was assessed. Oxytetracycline and formalin displayed a chromosome-damaging potential that remained for 18 days. The macroalgae-enriched diet evidenced a solid genoprotection against the three agents, revealing a broad-spectrum action. Oxytetracycline and formalin induced an erythrocyte population instability (translated into an aging effect), counteracted by algae supplementation, which seems to convey erythropoiesis promoting factors. Overall, the benefits given by the algae supplementation recommend its adoption within a framework of sustainable aquaculture practices, namely as a prophylactic measure to mitigate productivity losses when oxytetracycline and formalin are used.