Grouper Larvae Research Articles

The early life microbiome of giant grouper (Epinephelus lanceolatus) larvae in a commercial hatchery is influenced by microorganisms in feed

Fish health, growth and disease is intricately linked to its associated microbiome. Understanding the influence, source and ultimately managing the microbiome, particularly for vulnerable early life-stages, has been identified as one of the key requirements to improving farmed fish production. One tropical fish species of aquaculture importance farmed throughout the Asia-Pacific region is the giant grouper (Epinephelus lanceolatus). Variability in the health and survival of E. lanceolatus larvae is partially dependent on exposure to and development of its early microbiome. Here, we examined the development in the microbiome of commercially reared giant grouper larvae, its surrounding environment, and that from live food sources to understand the type of bacterial species larvae are exposed to, and where some of the sources of bacteria may originate. We show that species richness and microbial diversity of the larval microbiome significantly increased in the first 4 days after hatching, with the community composition continuing to shift over the initial 10 days in the hatchery facility. The dominant larval bacterial taxa appeared to be predominantly derived from live cultured microalgae and rotifer feeds and included Marixanthomonas, Candidatus Hepatincola, Meridianimaribacter and Vibrio. In contrast, a commercial probiotic added as part of the hatchery’s operating procedure failed to establish in the larvae microbiome. Microbial source tracking indicated that feed was the largest influence on the composition of the giant grouper larvae microbiome (up to 55.9%), supporting attempts to modulate fish microbiomes in commercial hatcheries through improved diets. The marked abundances of Vibrio (up to 21.7% of 16S rRNA gene copies in larvae) highlights a need for rigorous quality control of feed material.

Characteristics of Morphological Changes in Fins according to Larval Growth of Red Spotted Grouper, Epinephelus akaara.

This study investigated the fin development and morphological characteristics according to larval growth in order to obtain information on behavioral characteristics and optimal stocking density during red seed grouper seed production. To examine the growth and fin development process of the larvae, we randomly sampled at 1, 3, 5, 7, 9, 10, 11, 13, 15, 17, 19, 20, 25, 30, 39, 45, 51, and 72 days after hatching. External morphology was observed and measured using an optical microscope. To observe skeletal development, larvae at 13, 20, 30, and 72 days after hatching were fixed in formalin and stained for cartilage and bone examination. At 9-10 DAH, red spotted grouper larvae (2.74±0.1 to 3.0±0.2 mm TL) exhibited a second dorsal fin spine and pelvic fin spine, which subsequently elongated. At 19-20 DAH, the larvae (5.7±0.1 to 6.1±0.1 mm TL) have the lengths of the second dorsal fin spine and pelvic fin spine average 34% and 31% to total length, respectively. From 30 to 72 DAH (12.6±0.4 to 56.0±0.2 mm TL), the length of the second dorsal fin spine and pelvic fin spine to total length decreased from 27% to 8% for the dorsal fin and 21% to 14% for the pelvic fin, respectively. At 30 DAH (12.6±0.4 mm TL), the larvae reached the complete count of fin rays in each fin. At 39 DAH (20.28±3.07 mm TL), the larvae had fin shapes similar to those of adults. At 13-30 DAH (4.2±0.1 to 12.6±0.9 mm TL), barbs and spinules were distributed along the ridges of the second dorsal and pelvic fin spines. However, at 72 DAH, these barbs and spinules were no longer observed on the fins. During the seed production process, red spotted grouper larvae tend to cluster in the morning, and during this time, entanglement of barbs and spinules on the second dorsal and pelvic fin spines can lead to mortality. Therefore, it is considered essential to focus on managing the behavioral patterns and appropriate rearing density of red spotted grouper larvae from the emergence of barbs and spinules on the second dorsal and pelvic fin spines until they regress and metamorphosis is completed.

Changes in aerobic metabolism associated with the settlement transition for the leopard coral grouper (Plectropomus leopardus)

Metamorphosis is a critical aspect of coral reef fish ecology. This developmental milestone marks changes in form and function that permit successful transition of pelagic larvae to the demersal lifestyle on coral reefs. However, we know very little about the physiological changes that occur during this period, specifically potential changes in energetics associated with swimming. This is critical, as swimming is the mechanism by which pelagic larvae find a suitable reef on which to settle. Coral grouper larvae (Serranidae: Plectropomas leopardus) were collected at night as they came into the vicinity of a fringing reef to settle, and their physiological metamorphosis was characterized. Larvae and 24 h-settled juveniles were exposed to an endurance swimming test at ecologically relevant swimming speeds, and oxygen uptake rates were measured during activity. To describe how aerobic and anaerobic properties of tissues change during metamorphosis, we also measured whole body citrate synthase and lactate dehydrogenase activity, respectively, as well as mitochondrial density in the trunk and pectoral fins. Our approach accurately measures the oxygen uptake rates these life stages need during the recruitment process, with larvae having a 74% higher mass-specific oxygen uptake rate (ṀO2) than settled juveniles despite swimming at speeds that are only 1.5 body-lengths per second (BLs−1) faster. Citrate synthase activity significantly decreased upon settlement; as larvae had 3.7 times higher activities than juveniles, suggesting that rapid changes in aerobic metabolism of tissues may be an important process during metamorphosis in this species. In contrast, lactate dehydrogenase did not significantly differ upon settlement. These findings highlight some physiological modifications that pelagic coral grouper larvae undertake within 24 h that contribute to successfully settling onto a coral reef.

Structural Equation Modeling (SEM) of the interaction between cholecalciferol treatment and external factors in the incidence of vertebrae malformations in the hybrid grouper Epinephelus fuscoguttatus X Epinephelus polypehadion

Vitamin D3(VD3), also known as cholecalciferol plays a crucial role in maintaining calcium and phosphate homeostasis and has the potential to suppress bone malformations in fish larvae. However, external factors during growth also significantly influence the development of fish larval bones. Understanding the complex interaction between VD3 treatment and these external factors is crucial for optimizing therapeutic potential and effectively treating bone anomalies. SEM (Structural Equation Modeling) offers a comprehensive framework to explore these interactions by considering multiple variables simultaneously and examining their interrelationships. This study aimed to determine the impact of VD3 and its relationship with other external factors on the incidence of bone malformations in hybrid grouper larvae (Epinephelus fuscoguttatus X Epinephelus polyphekadion, EFEP). The treatments included a dose of 1.9 IU/g of VD3 in the feed and control group without VD3. All treatments received standard enrichment ingredients including vitamin C, taurine, and commercial enrichment (*SELCO). The enrichment was applied to rotifers (3 – 25 days after hatching, DAH) and artificial feed (25 – 35 DAH). The treatment was conducted in two batches, during the dry season (batch 1) and the rainy season (batch 2), to explore the seasonal impact on bone malformations. Results indicated that VD3 reduced the incidence of bone malformations in EFEP hybrid grouper fry by 1.14–1.65 times. SEM analysis revealed that spawning timing, egg quality, and water quality significantly impacted the occurrence of bone deformities, influencing malformations directly and indirectly through bone mineral content. This study demonstrated that bone malformations can be result from deficiencies in calcium, excess potassium and sulfur, and the presence of bromine in bone.

Movement Behavior of the Dusky Grouper Epinephelus marginatus (Lowe, 1834) in Early Life Stages

The dusky grouper (Epinephelus marginatus) is a vulnerable predatory fish found in the Atlantic and Indian oceans, and in the Mediterranean Sea. This study investigates the movement patterns of grouper larvae (151 individuals) during their first feeding period (three to ten days post hatching) through laboratory experiments offering rotifers (Brachionus sp.) and copepod nauplii as food. High-speed cameras and imaging techniques including bright field microscopy, matched filters, and holography captured rapid displacements (up to 25 body lengths per second), peduncle caudal beats (up to 40 beats s−1), turns, and resting periods. Reynolds numbers ranged from <45 for routine swimming to 222 for burst swimming. Specific behaviors, including changes in swimming velocity and body movements, were observed from three days post hatching, when feeding begins, suggestive of an array of responses to environmental forcing, predator avoidance, food search, and feeding success. These findings provide insights into the critical movement performances of E. marginatus larvae, which help to unravel their ecological interactions and survival strategies. Understanding grouper larval swimming behavior is pivotal for devising effective cultivation strategies aimed at replenishing wild stocks and enhancing production for human consumption.

PEMELIHARAAN LARVA HYBRID KERAPU CANTIK (Epinephelus sp) DI CV. JAYA UTAMA ABADI DESA KALIASEM, KECAMATAN BANJAR, KABUPATEN BULELENG, SINGARAJA BALI

Hatchery technology for producing grouper seeds has developed widely and massively, one of which is to produce hybrid larvae. To produce beautiful hybrid grouper larvae, there are many factors that must be considered because they greatly influence the success of larvae production, including food management, water quality management and others. The purpose of writing this Final Practical Scientific Work Report is to find out the activities for rearing beautiful hybrid grouper larvae resulting from a cross between male batik grouper and female tiger grouper. Activities include egg handling, larval rearing, feed management, water quality management, grading and harvesting. Observations were carried out at the CV hatchery unit. Jaya Utama Abadi for 3 months from 15 February to 15 May 2021. Data obtained from survey activitieswith an apprenticeship pattern, namely taking part in rearing activities for beautiful hybrid grouper larvae. Primary data is collected through interviews and direct observation in the field, while secondary data is obtained through data or activity reports and other supporting literature, then processed.and analyzed quantitatively descriptively. Observation result The fertilized hybrid eggs are then hatched in a larval rearing tank using a volume of 6 m3 water of 5 unitswith a total number of eggs spread of 50,000 eggs/tub, or a total of 250,000 eggs, it produces an average hatchability of 54.4%, until they develop into 136,000 larvae and succeed in achieving a harvest with an average size of 3 cm/head of 11,900 eggs and a level of SR 88 %.

A Comprehensive Biochemical Characterization of Hybrid Grouper Larvae (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) during Yolk-Sac Larval Development.

To investigate the shifts in the biochemical composition of hybrid grouper during the early larval stages, we collected samples at various developmental milestones, spanning from newly hatched larvae (stage I) to 4 days after hatching (stage V). Our findings revealed several notable trends: (1) The total length of hybrid grouper larvae exhibited a significant increase as the yolk-sac absorption progressed from stage I to V. Concurrently, there was a marked decrease in yolk volume and oil volume during the transition from stage I to III, followed by a gradual decline from stage III to V. (2) Dry weight and total lipid content displayed a rapid reduction throughout the larval development period, while the total protein content exhibited a declining trend. (3) The concentrations of triacylglycerols and wax esters/steryl esters decreased considerably, particularly at stage V. However, no differences were observed among the contents of ketones, hydrocarbons, and sterols. (4) As yolk-sac larvae developed from stage I to V, a significant reduction was observed in the levels of essential amino acids (EAAs), such as leucine, valine, isoleucine, phenylalanine, glycine, alanine, serine, proline, and tyrosine. This trend was also observed for non-EAAs and total amino acids, with fluctuations in the content of other amino acids. (5) There was a significant decrease in the levels of specific fatty acids, including C16:0, saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), C18:0, 18:1n-9, and C20:4n-6. In contrast, the contents of C22:6n-3, polyunsaturated fatty acids (PUFAs), n-3 PUFA, n-6 PUFA, and the combination of docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA), as well as the DHA/EPA ratio, remained stable from stage I to III but declined thereafter. (6) During the early developmental stages, the utilization sequence of fatty acids followed a pattern of prioritizing SFAs, followed by MUFAs, n-6 PUFA, and n-3 PUFA. These findings provide further insights into the nutritional priorities of hybrid grouper larvae during their early development, with a particular emphasis on lipids and fatty acids as vital energy sources. Additionally, our results highlight variations in the efficiency of utilization among different types of fatty acids, while protein utilization remained relatively stable, characterized by the selective consumption of amino acid content.

Cantang Group (Epinephelus Fuscoguttatus >< Epinephelus Lanceolatus) Hatcheries At The Blitok Installation Of Breach Water Cultivation Fisheries Center (BPBAP) Situbondo, East Java

To achieve success in the maintenance of cantang grouper requires mastery of techniques in good hatchery of cantang grouper (Epinephelus fuscoguttatus >< Epinephelus lanceolatus) in order to produce optimal productivity both in terms of quantity and quality. The aims of this study were: 1) To find out the development and growth rates in cantang grouper hatcheries (Epinephelus fuscoguttatus – lanceolatus), 2) To determine the condition of water quality in cantang grouper hatcheries (Epinephelus fuscoguttaus – lanceolatus), and 3) To determine the feasibility of cantang grouper hatcheries (Epinephelus fuscoguttaus – lanceolatus). The data analyzed in this study include data on growth, water quality, and business analysis. The results of the analysis showed that: 1) In a day the average length increase reached 0.074 cm and the percentage rate of increase in length of cantang grouper larvae for 29 days from the age of D30 – D58 was 7.4%. At the beginning of measuring the length of cantang grouper larvae, the average length was 1.12 cm and at the end of the observation the average value was 3.28 cm. 2) From the results of water quality maintenance, the temperature ranged from 29 – 31°C, oxygen dissolved 4.37 – 4.87 mg/L., pH 7.4 – 7.9, and salinity 28 – 30 ppt, 3) In terms of financial or business feasibility the cantang grouper hatchery activity at the Blitok BPBAP Situbondo Installation can be said to be feasible to do and profitable with a net profit of Rp. 665,904,233/year with an R/C ratio of 3.7. Break Event Point (BEP) price of Rp. 111,539,155/year with production BEP reaching 37,179 heads. Payback Period (PP) for 1 year.

Growth models in aquaculture for hybrid and natural groupers based on early development stage

Grouper has been highlighted as current hot species for marine aquaculture in China, so it is vital to master its growth performance in early development stage and understand growth trend of it. However, there are few detailed reports on the growth model and biological parameters in the early growth of grouper. The aim of this study is to discuss and compare the applicability of growth indexes and 10 biological growth models in larval and juvenile stage of hybrid and natural groupers, then to evaluate the optimum model. Pearl gentian grouper (PG) and kelp grouper (KG) were selected. The growth data of grouper larvae and juvenile were chosen. Absolute growth (AG), relative growth rate (RGR) and specific growth rate (SGR), and the thermal-unit growth coefficient (TGC) were calculated. Ten nonlinear models, such as Logistic, Gompertz,Von Bertalanffy, Generalized Weibull, Janoschek, Schnute and et al., were used to fit growth. Models were evaluated and selected by Akaike information criterion (AIC) method, the values of RMSE, MAE and R2, parameter significance level and iterations. Fitting results showed that compared with AG, RGR and SGR, TGC has higher fitting degree, especially for fitting weight (R2 > 0.99). In larval stage, Schnute model had the highest best fit ratio (75%), and minimum number of iterations (< 71), with more than two significant parameters (P < 0.001). In juvenile stage, the beat fitting ratio of Janoschek model evaluated by AIC was 25%, and that by RMSE, MAE and R2 was 50%, which was higher than other models. It also had low iteration times and high significant level (P < 0.05). For model evaluation, best fitting result evaluated by AIC method was different from that evaluated by RMSE, MAE and R2. It is more reliable to combine the two methods for model evaluation. The growth curves generated by optimum models showed that the growth characteristics of larvae is exponential, and in juvenile stage, PG maintained accelerated growth but the growth rate of KG gradually decreased. In summary, the optimum model of larval stage was Schnute model and that of juvenile stage was Janoschek model; 4-parameter models have high robustness and accuracy for fitting growth; Compared with KG, PG grows faster and is more suitable for aquaculture.

Using a transcriptomic approach to understand poor growth performance in farmed orange-spotted grouper (Epinephelus coioides) larvae: a case study in a commercial hatchery

ABSTRACT The orange-spotted grouper (Epinephelus coioides) is one of the most popular fish in aquaculture due to its high economic value. However, the random occurrence of slow-growing population has led to profit loss. Therefore, transcriptomic analysis was performed to identify the molecular mechanisms involved in driving slow and fast growth, towards addressing this issue. Results show that low expression of developmental genes such as bone morphogenetic protein 1 (BMP 1) and somatostatin (SST), as well as GH/IGF axis-related genes (IGF-1, IGF2, IGFBP1, IGFBP2) and its downstream signalling pathways are correlated with the metabolism and digestive-system-related pathways in slow-growing groupers. Enrichment analysis further revealed that cellular process and biological regulation, as well as several pathways including glycolysis/gluconeogenesis, linoleic acid metabolism, protein digestion and absorption, and cholesterol metabolism were differentially expressed in slow-growing groups. The findings implied that the genomic architecture of growth between the different families raised and the likely problem of inbreeding have led to significantly reduced growth. It is also suggested that better husbandry practices (optimal dietary requirement) is also vital in supporting the success of a genetic improvement programme. These findings recommend growth improvement of orange-spotted groupers via molecular monitoring and artificial selection, complemented by specific dietary feeding.

THE FEEDING MANAGEMENT OF GROUPER (Epinephelus sp.) LARVAE FROM THE CROSS-BREEDING SPAWNING PRODUCT IN BULELENG BALI

High mortality in larvae emerges due to less suitable size and nutritional contents of the feed for larval requirement. Therefore, live feed management is one of the successive factors in many grouper hatcheries to reduce high mortality risk in larval stage and provide good nutritional value in fish. This article reviewed the feeding management of grouper larvae and the obstacles occurred during the feeding management within the larval rearing period in Buleleng, Bali. The grouper larvae were produced from the cross-breeding process between female tiger grouper (E. fuscoguttatus) and male marbled grouper (E. polyphekadion). Rotifers (Branchionus plicatilis) were enriched with marine green microalgae (Nannochloropsis oculata) at 2 × 105 ind/ml. Rotifers were then fed to the larvae at 1-3 ind/ml. This feeding application was performed when the larvae was at 2-7 DAH (days after hatching). Artemia salina was fed to the 17-DAH larvae at 0.2-0.5 ind/ml, then increased at 8 ind/ml as the larvae reached 27 DAH with four-time feeding frequency. Also, commercial feed was provided for the larvae at 15 DAH and small shrimp (Acetes sp.) was fed to the 40-DAH larvae for supplement. This feeding management could produce a good absolute length growth rate at 22.3 mm on 35 days of rearing. However, high mortality rate was still occurred due to cannibalism, high stocking density of rotifers, and fluctuated weather that decreased the live feed supply. Thus, additional nutrient enrichment and optimal larval consumption observation should be performed to reduce high mortality rate, cannibalism, and weather condition influence.

Some Hatchery Parameters of Three Species of Groupers: Tiger Grouper (Epinephelus fuscoguttatus), Humpback Grouper (Cromileptes altivelis), and Leopard Coral Grouper (Plectropomus leopardus)

Three species of groupers, including tiger grouper (Epinephelus fuscoguttatus), humpback grouper (Cromileptes altivelis), and leopard coral grouper (Plectropomus leopardus), have been successfully cultivated. However, the constraints on larviculture that have been described still arise in the hatchery. This study compares several hatchery parameters in these three grouper species representing three different genera (Epinephelus, Cromileptes, and Plectropomus). The egg incubation and larval rearing were carried out in a concrete tank (3 x 3 x 1.2 m3) filled with 6-7 m3 seawater. Eggs were stocked with a density of 100,000 eggs/tank. The grouper larvae were reared until they became juvenile. The eggs were incubated until they were hatched in the same container and media as larval rearing. Larvae were reared until 60 dah (days after hatching), and data were taken from the rearing for three cycle's larval culture. Management of grouper larval rearing follows the Good Fish Hatchery Method (Cara Pembenihan Ikan yang Baik/CPIB) based on Indonesian National Standard (Standar Nasional Indonesia/SNI). The experimental parameters were egg diameter, hatching rate, larvae mouth opening width, survival activity index (SAI), larvae development, and total body length growth. The several hatchery parameters in three grouper fish species are significantly different. The tiger grouper has the best larval performance.

Control of gonadal maturation and sex in grouper

Protogynous groupers, belonging to the subfamily Epinephelinae, are among the most crucial fishery targets in the Asian countries. Currently, several grouper species are cultured, providing seed for the aquaculture industry. However, cultivation grouper larvae are unstable. Thus, the improvement of aquaculture technology of grouper production is needed. Appropriate managing the reproduction and sex of the target parent fish is vital to enhance the efficiency of aquaculture. This paper reviews new technologies for induction of gonadal maturation and control of sex in groupers. The dynamics of androgen-producing cells, which are essential for a sex change, are also discussed.

TEKNIK PEMELIHARAAN LARVA IKAN KERAPU CANTANG (Epinephelus sp.) DI SBB 88, DESA PASIR PUTIH, KECAMATAN BUNGATAN, KABUPATEN SITUBONDO

This research was conducted at CV. Abundant Seed Facility (SBB) 88, Pasir Putih Village, Bungatan District, Situbondo Regency. The purpose of this study was to determine the hatchery of cantang grouper from larval rearing, feeding to harvesting and post-harvest at the Abundant Seed Facility (SBB) 8 Situbondo, as well as to obtain data and information on the production yield, quantity, and quality of seeds available at the Abundant Seed Facility. (SBB) 8 Situbondo. The method used in this research is the descriptive method, with data collection techniques including primary data and secondary data. This data collection was carried out by observation, interviews, and active participation. SBB 88 is a household scale hatchery that has been certified by CPIB and has individual ownership status. SBB 88 was first established in 2007 with a land area of ​​900 m2, the reason it is numbered 88 is that the number of tanks in the maintenance room is 8 tanks. The rearing process for cantang grouper larvae at SBB 88 was carried out indoors, starting with egg-laying, hatching eggs, and grading from D26 – to D40. In one cycle it takes about 2 months with a seed harvest of 3 cm - 4 cm in size. The calculation of the hatching rate (HR) obtained was 80%, from 100,000 eggs that were stocked and hatched as many as 80,000 larvae, the yield obtained was 25,500 seeds from 80,000 larvae so the SR obtained was 31.87%.

Effects of dietary lipid, L-carnitine and L-lysine supplementation on the growth performance and body composition of Epinephelus lanceolatus larvae

The effects of different combinations of dietary lipid, L-carnitine and L-lysine on the growth performance and fatty acid profiles of larval grouper Epinephalus lanceolatus were evaluated. Eight treatment diets were formulated based on a 2x2x2 factorial design, namely 5 and 14% dietary oil mixture (3:1 fish oil/soybean oil), 0 and 0.5% L-carnitine and 0 and 2.83% L-lysine. Each diet was randomly assigned to triplicate groups of ten 0.08g E. lanceolatus larvae for 42 days. The grouper larvae fed with diets containing 14% lipid had significantly higher weight gain percentages than those fed with diets containing 5% lipid. The weight gain percentage of the grouper larvae fed with a diet containing both 14% lipid and 0.5% L-carnitine without added L-lysine was found to be the highest, while the addition of dietary 2.83% L-lysine failed to have any additive effect on the growth performance. With the dietary lipid being 14%, not only dietary L-carnitine but also L-lysine is able to decrease lipid and increase protein levels in grouper muscle. The supplementation of dietary L-carnitine with a high level of lipid is also able to reduce liver lipid level of groupers. The levels of n-3 highly unsaturated fatty acid (n-3 HUFA) analyzed from muscle and liver of grouper larvae fed with diets supplemented with L-carnitine were significantly lower than those of grouper larvae fed with diets devoid of L-carnitine. This study indicated that the diets containing a high lipid level supplemented with L-carnitine are able to enhance the growth performance of grouper larvae.

PENGELOLAAN PAKAN DAN PENGENDALIAN PENYAKIT LARVA KERAPU TIKUS (Cromileptes altivelis)

Larval health is an important problem faced by the hatchery of humback grouper (Cromileptes altivelis). One of the factors that influence larval mortality is feed management and disease control in humback grouper larvae. Methods of data collection is done by means of direct interviews, active participation and observation. Feeding the larvae was started when the larvae were 2 days old with the first feed being Nannochloropsis occulata. Then Rotifera was given when the larvae were 2-4 days old with a density of 5 individuals/ml. Feed in the form of Artemia is given when the larvae are 20 days - 40 days old. Level 1 pellet feed was given when the larvae were 8-10 days old. The disease that often attacks humback grouper larvae is VNN (Viral Nervous Necrosis) with the characteristics of infected larvae are weak movement, larvae float on the surface, decreased appetite and larvae lying on the bottom of the pond. The bacterium that attacks the larvae is Vibrio alginolyticus. Treatment of Vibrio alginolyticus can use antibiotics but has bad side effects. While alternative medicine can use drugs from natural ingredients.

SURVIVAL RATE of TIGER GROUPER LARVA (Epinephelus fucoguttatus) HOUSEHOLD SCALE ON THE NORTH COAST of BALI

Tiger grouper (Epinephelus fuscoguttatus) hatchery at the household scale has contributed to the increase in national grouper seed production. The main problem in tiger grouper cultivation is the availability of superior seeds. Where superior tiger grouper seeds must have fast growth, be resistant to new environments, low FCR, have perfect morphology and be resistant to. Superior seeds of tiger grouper can be seen from the value of Survival Rate (SR), where superior seeds will have a much higher SR when maintained. The purpose of this study was to determine the Survival Rate of tiger grouper hatchery in household-scale hatcheries located on the North Coast of Bali as the main parameter and water quality as a supporting parameter. Methods of data collection is done by using 4 ways: survey, active participation, observation, and interviews. Survival rate data analysis was carried out by performing calculations based on the SR calculation formula and analyzed descriptively. The results of observations of water quality are classified as good for the value of Salinity (33-35 ppt), Temperature (28-29.4 oC), and DO (6-6.5 ppm). While the pH value can be said to be not good for tiger grouper hatchery and rearing with a pH value of (7.3-7.4). The result of the calculation of the Survival Rate is 20% with a total of ± 24,000 seeds. From the percentage of survival rate, it can be said that the survival rate of tiger grouper larvae in this household-scale hatchery is still low. However, it should be noted that a low survival rate in grouper hatcheries does not always affect the value of profits and losses of a grouper hatchery business.

Health Management of Humpback Grouper Larvae (Cromileptes altivelis) in BBRBLPP Gondol

Larvae health management is a key factor in the hatchery of humpback grouper (Cromileptes altivelis) to prevent mass larval deaths and cause financial losses. Management of humpback grouper larvae health includes larval rearing, larval feed management and larval disease control. The primary data collection method was carried out in 3 ways, namely observation, active participation and interviews. Secondary data retrieval by studying literature from various related sources. The humpback grouper larvae were reared in the hatchery to control the temperature and condition of the larvae. Larval ponds are sterilized with 3-5 ppm chlorine in the morning and rinsed thoroughly so that no chlorine remains. Larvae were reared from the age of 1 day to 45 days. Feeding the larvae was started when the larvae were 2 days old with Nannochloropsis occulata. Rotifers were given when the larvae were 2-3 days old with a density of 5 individuals/ml. Artemia was given when the larvae were 20 days old until the age of 40 days. Pellets are given when the larvae are 8-10 days old with a pellet size of level 1. The pellet size continues to increase according to the larva's mouth opening. The disease that often attacks larvae is Viral Nervous Necrosis (VNN). The characteristics of larvae infected with VNN are reduced appetite, weak movement, larvae float on the surface and lie on the bottom of the pond. VNN attacks can only be overcome by prevention. The bacteria that often attack the larvae are Vibrio alginolyticus. Vibrio alginolyticus can be treated with antibiotics or non-antibiotics. The use of antibiotics is not recommended because they have negative side effects, so you can use other alternative medicines derived from herbal plants (phytopharmaceuticals).

Effects of Zn on growth performance, immune enzyme activities, resistance to disease and intestinal flora for juvenile pearl gentian grouper(Epinephelus lanceolatus♂×Epinephelus fuscoguttatus♀) under low fishmeal diet

The effects of adding increasing Zn concentrations to fish feed on the growth performance, antioxidant enzyme activity, disease resistance, and intestinal flora abundance and diversity of hybrid grouper larvae (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀) were determined within an 8-week feeding trial period. Zn of graded levels (0 (T0), 20 (T20), 40 (T40), 60 (T60), 80 (T80), 100 (T100) and 150 (T150) mg Zn/kg diet as zinc sulfate) was added to the basal diet and fed to experimental fish with an initial mean weight of 12.00 g.The fish were challenged by Vibrio harveyi for 7 days. Results showed that the survival rate of the dietary Zn groups was obviously higher than that of T0 (P < 0.05). T0 group had the lowest specific growth rate and weight gain rate. The hepatic superoxide dismutase activity of the dietary Zn groups was significantly higher than the T0 group(P < 0.05). T20 group had the lowest hepatic malondialdehyde content. The abundance of Proteobacteria in the midgut decreased significantly (P < 0.05) and the abundance of Bacteroidetes and Firmicutes increased with increasing zinc levels. The optimal dietary Zn inclusion level was 44.52 mg/kg diet, based on the polynomial regression analysis model of WGR for juvenile hybrid grouper.

Integrated response of growth performance, fatty acid composition, antioxidant responses and lipid metabolism to dietary phospholipids in hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) larvae

Dietary phospholipids supplementation is essential for normal development of fish larvae due to their limited phospholipid biosynthetic ability. The present study was conducted to investigate the effects of dietary phospholipids on growth performance, fatty acid composition, antioxidant capacity and lipid metabolism of larval hybrid grouper. The larvae (40 day after hatching, 0.37 ± 0.01 g) were fed the diet with graded level of phospholipids (1.87, 3.61, 5.53, 7.25 and 9.69%) four times daily for 23 days. Results showed that the specific growth rate of grouper larvae was significantly improved with the increase of dietary phospholipids, and optimal dietary phospholipids was estimated to be 9.17%. Fatty acids composition of whole fish body and liver was highly reflective of dietary fatty acid profile. In addition, the increase of dietary phospholipids resulted in a significantly elevated hepatic crude lipid and triglyceride content in a dose-dependent manner. The analysis of gene expression revealed that increased dietary phospholipids did not produce any statistical effect on the expression of lipogenesis genes including LXRɑ, FAS and ACC, but significantly facilitated the expression of DGAT2, a rate-limiting enzyme involved in triglyceride synthesis. The expression of genes, CPT1, involved in β-oxidation was not significantly influenced as dietary phospholipids increased. However, phospholipids inclusion significantly reduced the expression of ATGL, an rate-limiting lipolytic enzyme. Additionally, the supplementation of dietary phospholipids significantly elevated the activity of antioxidant relate enzymes, CAT, SOD and T-AOC, but significantly decreased the MDA content, an end product of fatty acid peroxidation. In summary, dietary phospholipids supplementation was beneficial in improving growth performance and antioxidant capacity of grouper larvae, and meanwhile, promoted hepatic lipid deposition through regulating the synthesis and hydrolysis of triglyceride.