Studies on the broodstock production and larval rearing of Coral demoiselle Neopomacentrus nemurus (Bleeker 1857)

Steps taken for broodstock development of Neopomacentrus nemurus, Coral demoiselle (Bleeker, 1857) in a hatchery, its spawning and development of egg to the juvenile stage are described. Among the three treatments tried, only the trial using Parvocalanus crassirostris nauplii as the first diet helped in the development of larvae. Larval and post‐larval growth was studied for a period of 65 days post hatch. The larva measured 2–2.4 mm in total length at the time of hatching. The mouth size of larva at the time of hatching measured 237.92 µm. By the 5th day, the width of the larval body had significantly increased. All the fins were conjoined, except for the caudal fin which had begun its appearance on the 2nd day itself. The digestive system was functional by the 5th day and the copepod remains were seen in the digestive tract. The larva metamorphosed by the 15th day with fully developed fins and fin rays. On the 20th day, the larval body had begun to display signs of fin pigmentation. The larva assumed adult pigmentation by the 35th day. By the 65th day, the larva grew to a total length of about 27 mm and weighed about 0.56 g.     

Effect of temperature increase on the embryonic development of Patagonian red octopus Enteroctopus megalocyathus in controlled culture

One of the major problems involved in the controlled cultivation of Patagonian red octopus (Enteroctopus megalocyathus) is its long embryonic period ranging between 150–176 days, after which the hatching of planktonic paralarvae is achieved. The effect of temperature on the incubation of E. megalocyathus eggs was studied with the aim of establishing if a temperature higher than 12°C is effective to accelerate the embryonic development without altering their morphological and physiological conditions. Fertilized eggs obtained under controlled conditions at 11°C ± 0.1 were randomly distributed in 12 water baths of 30 L at 4 temperatures: 12, 14, 15 and 16°C ± 0.1°C. The experiment lasted until egg hatching occurred.The embryo growth rate was accelerated at 15–16°C, so the time spent in embryonic development can be reduced in 15% when compared with embryo development obtained from eggs incubated at 12°C. The embryos showed no significant differences in the final survival and were morphometrically similar in all stages of development at all temperatures. The increase in temperature from 12 to 16°C, even if it allowed a better growth, had high metabolic costs for embryos of E. megalocyathus. The activities of lipases and proteases were affected by interaction between temperature and the embryo stage, with high lipase activity observed in embryos of stage XV incubated at high temperatures and the highest levels of trypsin and chymotrypsin in stage XX at 14°C. The results suggest that 15°C could be the limit temperature to increase growth.     

Growth performance and nutritional composition of Sepia pharaonis under artificial culturing conditions

This study investigated the growth performance and nutritional composition of scale artificially cultured cuttlefish Sepia pharaonis. Juveniles were cultured in an open‐culturing cement pool system for 120 days. The body weight increased from 10.21 ± 1.44 g to 570.71 ± 126.32 g from 50 days old to 170 days old, and the average growth rate was 4.67%. The proximate, amino acid and fatty acid compositions of S. pharaonis muscles were analysed every 40 days to compare the quality. The cultured S. pharaonis were rich in essential amino acids (EAAs), functional amino acids (FAAs), docosahexaenoic acid (DHA) and polyunsaturated fatty acids (PUFAs), which accounted for 32%, 46%, 28% and 54% (dry weight) respectively. Total amino acids (TAAs) and EAAs exhibited a clear distinction between ages, and significant differences were observed among the levels of individual amino acids, including Pro, Ala, Asp and Lys, which were significantly higher at 130–170 days old than at 50 days old (p < 0.05). Although the total saturated fatty acids, monounsaturated fatty acids and PUFAs were statistically similar between ages, C17:0, C22:6 n‐3 and PUFAs were higher at 130–170 days old than at 50 days old (p < 0.05). The results indicate that large‐scale artificial culture of S. pharaonis can be achieved under the conditions of a cement pool. This study also provides new information regarding the growth performance and nutritional composition of cultured S. pharaonis, which will contribute to the development of aquaculture practices for this species.     

Embryonic development of Ganga river prawn Macrobrachium gangeticum (Bate)

Macrobrachium gangeticum (Bate) are commercially valuable prawns that are broadly distributed in the Ganga river that flows from northern to eastern India. We studied embryonic development from cleavage (blastomeres), segmentation, formation of optic vesicle, eye pigment development to larva formation, as these data are largely unknown in this species. We conducted this study using mature M. gangeticum broodstock placed in freshwater tanks. Just after spawning, females were kept in separate aerated tanks, where fecundity was estimated from the total number of eggs. Thereafter, egg samples from berried females were used to study their embryonic stages. The correlation coefficient between size and prawn weight, egg weight, egg number, body weight and egg mass of different sizes of prawns was analysed. Our results show that an increase in prawn size led to an increase in egg weight and egg number while decreases in body weight:egg mass ratio was noticed. Further results indicate that an increase in prawn weight had a positive impact on egg weight and egg number. The embryo development stages were used in this study as a tool to evaluate the development process of the prawn in a hatchery environment.     

Embryonic and larval development of serpae tetra Hyphessobrycon eques (Steindachner, 1882)

In this study, the embryonic and larval development stages of one of the most important ornamental fish serpae tetra (Hyphessobrycon eques) are described. The early life stage is documented from fertilization until the beginning of the juvenile period. The fertilized eggs (the average diameter = 938.55 ± 35.20 µm) were incubated at a water temperature of 26 ± 0.5°C. The cleavage finished in 1:10 hr (=h) and the early blastula stage occurred at 1:26 hr post fertilization (hpf). The gastrulation started at 3:05 hpf, and 50% epiboly was observed at 3:25 hpf. Segmentation stage was monitored at 7:26 hpf. Embryonic developmental stage was completed and hatching occurred 20–21 hpf. The total length (TL) of newly hatched larvae was 2.64 ± 0.21 mm. The larval development of serpae tetra was divided into four different periods: Yolk‐sac larva (1–4 DAH, TL = 2.77 ± 0.09 mm ‐ 3.85 ± 0.11 mm), preflexion larva (5–12 DAH), flexion larva (13–15 DAH, TL = 5.78 ± 0.46 mm on the 15th day) and post‐flexion larva (16–30 DAH, TL = 10.7 ± 0.27 mm on the 28th–30th days). The mouth and anus are closed at 1 DAH. The mouth and anus opened at 4 DAH. Exogenous feeding started on the 4th day. The first gulping of the swim bladder was on days 3. The larva begins to swim freely, and the yolk sac was completely consumed at 4 DAH. Histological structures of the eye and brain of new hatched larva were clearly identified at 1 day after hatching (DAH). According to histological findings, the digestive system (stomach, intestine) started to develop and the liver could be seen on the ventral side of the swim bladder at 5 DAH. No histological difference was observed between the anterior intestine and the posterior intestine at 15–16 DAH. The larval metamorphosis was completed, and the larvae transformed into juveniles at 28–30 DAH.     

Embryonic and larval development in the semelparous Nereid polychaete Hediste diversicolor (OF Müller, 1776) in Norway: Challenges and perspectives

Knowledge of broodstock manipulation, gametogenesis, artificial fertilization and larval nutrition is a prerequisite to reach a large‐scale production of the polychaete Hediste diversicolor. In this study, the characteristics of oogenesis and spermatogenesis and embryonic and larval development were observed. Moreover, the effect of temperature on embryonic development and effect of diets and sediment on earlier juvenile development were tested. Mature oocytes were characterized by a spherical shape with a diameter of about 200 μm. They showed radial symmetry with a large centric nucleus surrounded by four distinctive layers. Embryo cleavage started between 4 and 10 hr after fertilization, and developed to the swimming trochophore stage after 5–6 days after fertilization at 11°C. The rate of embryonic development increased with a temperature increase from 6.1 to 21.2°C. The trochophore larvae increased in length from day 9 and commenced differentiation into 3‐setiger stage larvae at day 12. The length growth of larvae until 7‐setiger stage was 0.43 mm/day when fed with fish feed, while those fed shellfish diet and smolt sludge both grew around 0.21–0.23 mm/day. The results suggest that fish feed is a superior diet compared to shellfish diets and smolt sludge for the early larval stage of H. diversicolor.     

Molecular cloning of heat shock protein 60 from Marsupenaeus japonicus and its expression profiles at early developmental stages and response to heat stress

Water temperature is an essential environmental factor in aquaculture that affects many aspects of organism, and a rise in water temperature stresses aquatic animals. HSP60 is a major component of the chaperone system and plays an important role in stress response. In this study, the full‐length cDNA sequence of HSP60 from Marsupenaeus japonicus was cloned for the first time, and the tissue distributions and expression profiles of MjHSP60 at the early developmental stages of M. japonicus and under heat stress were verified by qRT‐PCR. The full‐length cDNA sequence of MjHSP60 was 2,303 bp with the deduced amino acid (AA) sequence of 579 AA. MjHSP60 was expressed in all eight tested tissues of M. japonicus and was mainly expressed in the hepatopancreas under normal condition. MjHSP60 was expressed in all of the early developmental stages examined from the fertilized egg to the post‐larval stage, and the expression level of MjHSP60 peaked at zoea II and reached a trough at the transition periods between each two stages (N and M1) and showed a relatively stable expression level at the post‐larval stage. The expression level of MjHSP60 was significantly up‐regulated in the gills, muscle, heart, hepatopancreas and stomach at 3 hr post‐heat‐stress and showed varied sensitivity to heat stress. The expression profile of MjHSP60 in the hepatopancreas and gill showed a time‐dependent manner post‐heat‐stress and peaked at 3 hr post‐heat‐stress. The present study provided a basis for further studies for elucidating the function of MjHSP60 in the heat stress response and the early developmental stages of M. japonicus.     

The amino acid profiles in developing eggs and larvae of the freshwater Percichthyid fishes,trout cod,Maccullochella macquariensis and Murray cod,Maccullochella peelii peelii

Results on changes in the total amino acids (protein bound + free) and the free amino acids (FAA) in relation to development, from egg (unfertilised and/or fertilised) to yolk-sac resorbed larva, before first feeding, in two Percichthyid fish, trout cod, Maccullochella macquariensis and Murray cod, Maccullochella peelii peelii, which lay demersal, adhesive eggs, are presented. Throughout development, the FAA accounted for only a small proportion (0.19 % in fertilised eggs of both species) of the total amino acid pool. Nine essential amino acids (EAA) and eight non-essential amino acids (NEAA) were quantified in the amino acid pool at all stages of development. In both species, the total amino acid content decreased during the transformation (at 20 ± 1 °C) from newly hatched larva to yolk-sac resorbed larva. Overall, the changes in the TEAA and TNEAA reflected that of the amino acid pool. In trout cod, all but one EAA (lysine) and two NEAA (cysteine and glycine) decreased with ontogeny, from fertilised egg to yolk-sac resorbed larva. In Murray cod, however, the exceptions to the general decline were two NEAA (aspartic acid and glycine). In contrast, the FAA increased with development, the changes being reflected in both FEAA and FNEAA. Qualitatively, the predominant free amino acids in trout cod and Murray cod eggs were alanine, lysine, leucine and serine. Because the egg protein and the total amino acid contents declined with development, it is concluded that the rate of breakdown of yolk protein was higher than the anabolic and catabolic processes during embryogenesis. Data also suggest that in freshwater fish FAA are an unlikely primary energy substrate during embryogenesis.     

Replacement of fish oil with a DHA‐rich Schizochytrium meal on growth performance,activities of digestive enzyme and fatty acid profile of Pacific white shrimp (Litopenaeus vannamei) larvae

This trial was conducted to evaluate the effects of replacing dietary fish oil with Schizochytrium meal for Pacific white shrimp (Litopenaeus vannamei) larvae (initial body weight 4.21 ± 0.10 mg). Six test microdiets were formulated using Schizochytrium meal to replace 0 g/kg, 250 g/kg, 500 g/kg, 750 g/kg, 1000 g/kg or 1500 g/kg fish oil DHA. No significant differences were observed in survival, growth, final body length and activities of digestive enzyme among shrimp fed different diets (p > .05). No significant differences were observed in C20:5n‐3 (EPA) in muscle samples (p > .05). C18:3n‐3 and C20:4n‐6 in muscle increased as Schizochytrium meal replacement level increased (p < .05). No significant differences were observed in C22:6n‐3 (DHA) and n‐3 fatty acids among shrimp fed diets that algae meal replaced 0 g/kg ‐ 1000 g/kg of fish oil. Shrimp fed diet R150 had higher DHA content than other groups and had higher n‐3 fatty acids than that of shrimp fed diets R50, R75 and R100 (p < .05). C18:2n‐6, PUFA and n‐6 fatty acids in muscle increased, while n‐3/n‐6 ratio decreased with increasing algae meal replacement level from 0 g/kg to 1000 g/kg (p < .05). In conclusion, Schizochytrium meal could replace 1500 g/kg fish oil DHA in the microdiets without negatively affecting shrimp larvae survival, growth and activities of digestive enzyme.     

Embryonic and larval development of black skirt tetra (Gymnocorymbus ternetzi,Boulenger, 1895) under laboratory conditions

The embryonic and larval development of black skirt tetra, Gymnocorymbus ternetzi, are described under controlled laboratory conditions. In addition, major histomorphological changes and the allometric growth patterns during larval development have been described. The laboratory‐reared broodstock, that is 1 year of age, were spawned. Hatching occurred 20–21 h after spawning at 24 ± 0.5°C. The cleavage was finished in 2 h and the early blastula stage occurred at 2:04 hours after spawning. The gastrulation started at 3:20 hours and 30% epiboly was observed at 3:34 hours after spawning. Eight‐somite stage was observed at 08:33 hours. And embryonic developmental stage was completed at 21 h after spawning. The newly hatched larvae were 1442 ± 14.3 μm in mean total length (TL). The mouth opened at 3 days after hatching (DAH). The yolk sac had been totally absorbed and the larvae started to swim actively within 3–4 days. Notochord flexion began at 11 DAH. The metamorphosis was completed and the larvae transformed into juveniles at 32 DAH. In this paper, the full developmental sequence from egg to juvenile of G. ternetzi is described for the first time.     

The effects of constant and oscillating temperature on embryonic development and early larval morphology in longfin yellowtail (Seriola rivoliana Valenciennes)

Constant and oscillating egg incubation temperatures on embryonic development and early larval morphology were studied in longfin yellowtail (Seriola rivoliana Valenciennes). We investigated the effects of constant temperatures from 16 to 32°C on embryo development and larval morphology at hatch, and whether oscillating temperature during embryogenesis could lead to larval morphological variations. After hatching, larval morphology and development during yolk sac (YS) utilization were examined in larvae at constant temperatures and larvae at 25°C that had oscillating temperature during egg incubation. Hatching rates were > 75%, only decreasing to ~ 50% at 30°C. At constant temperatures, the largest larvae occurred at 22 and 24°C. The oscillating temperature did not affect the timing of embryo development but resulted in larger and smaller larvae with a smaller and bigger YS, respectively, with a similar hatching time. Therefore, a growth response occurred in embryos during a window of development before hatching, depending on the adaptive response to temperature (spawn‐specific). After hatching, most of the YS was absorbed within 24 hr in all treatments, and the growth of the larval head was a priority with an optimal development at 26°C. There was compensatory growth in smaller larvae resulting in similar sizes after YS utilization, but larvae showed variations in body structure that could be important in further aquaculture research.     

Effect of incubation temperature on the embryonic development and yolk‐sac larvae of the Pacific red snapper Lutjanus peru (Nichols & Murphy, 1922)

The effect of incubation temperature on embryonic development and yolk‐sac larva of the Pacific red snapper Lutjanus peru were evaluated by testing the effect of 26, 28 and 30°C, as this is the natural thermal interval reported during the spawning season of Pacific red snapper in the Gulf of California, Mexico. Sixteen developmental stages were observed. The incubation temperature affected the rate of development and time to hatching, being shorter at 30 than at 26°C, but no significant effect (P < 0.05) on larval length at hatching was registered. The depletion rate of yolk sac and oil globule was affected by incubation temperature particularly during the first 12 h post hatching (hph). At the end of the experiment (48 hph), significantly (P < 0.05) larger larvae were recorded at 26°C (TL = 3.22 ± 0.01 mm) than at 28° (TL = 3.01 ± 0.02 mm) and 30°C (TL = 2.97 ± 0.05 mm). Incubation of newly fertilized eggs at 26°C produces larger larvae, which may help to improve feeding efficiency and survival during first feeding.     

Effects of dietary L‐lysine supplementation on growth,body composition and muscle‐growth‐related gene expression with an estimation of lysine requirement of GIFT tilapia

An 8‐week feeding trial was conducted with extruded practical diets containing 320 g/kg of crude protein from plant‐based sources to determine the effects of L‐lysine on growth performances, muscle‐growth‐related gene (myoD, myogenine and myostatin) expression and haemato‐biochemical responses in juvenile genetically improved farmed tilapia (GIFT). Five isonitrogenous and isoenergetic diets were formulated to contain graded levels of lysine (14.3, 16, 17.5, 19 and 20.5 g/kg of diet). Each diet was randomly assigned to triplicate groups of 30 juvenile fish (5.2 ± 0.1 g), which were fed thrice a day (9:00, 13:00 and 17:00 hr). Maximum growth performances were observed in fish fed with lysine at 19 g/kg of diet. There was no significant (p > .05) effect on whole‐body composition and amino acids profile by dietary lysine supplementation. Significant (p < .05) changes were observed in relative expression of muscle‐growth‐related genes namely myoD and myogenine and in plasma metabolites by dietary lysine supplementation. In contrast, the relative expression of myostatin was not affected by dietary lysine supplementation. Broken‐line regression analysis and second‐order polynomial regression analysis of weight gain and N gain against dietary lysine levels showed that the dietary lysine requirement for juvenile GIFT tilapia was 18–18.3 g/kg of diet and 19.3–19.5 g/kg of diet, respectively.     

体外培养条件下三角帆蚌胚胎早期发育观察及胚胎发育生物学零度和有效积温分析

为了探寻三角帆蚌胚胎体外培养方法,本实验以解剖获得的雌雄配子为材料,使用与三角帆蚌体液等渗的平衡盐溶液(BSS)进行人工体外受精和体外培养,观察各阶段胚胎的形态特征,并分析计算不同胚胎发育阶段的生物学零度和有效积温。结果显示,在温度为(25±1)℃的BSS培养条件下,受精卵发育至第二极体排放、二细胞期、四细胞期、八细胞期、十六细胞期和桑葚期的时间分别为1.8、2.8、5.6、10.5、13.9和17.3 h,胚胎最长发育至桑葚期后停止发育。另外,池塘平均水温分别为26.5、28.1和29.2℃时,三角帆蚌胚胎发育至成熟钩介幼虫分别需要10、9和8 d,计算得出三角帆蚌胚胎发育的生物学零度为14.81℃,根据生物学零度计算胚胎发育至卵裂期、囊胚期、原肠期、膜内钩介幼虫期和成熟钩介幼虫的有效积温分别为12.95、25.99、42.27、69.21和118.14℃×d。研究结果初步尝试对三角帆蚌受精卵进行体外培养,并根据胚胎发育水温和时间获得三角帆蚌早期胚胎发育的生物学零度和有效积温,可为突破三角帆蚌全人工繁育技术奠定基础,对淡水贝类现代生物育种技术研发和种质资源保护具有重要意义。     

Effect of different dietary lipid levels on the reproduction of Rhamdia quelen (Quoy and Gaimard, 1824)

Lipids include some of the most important nutrients that affect the survival and growth of fishes in their early life stages. Lipid deficiency prior to spawning may significantly reduce egg production, hatchability and the number of surviving larvae. In this study, we investigated the effects of isocaloric diets containing 80, 140 and 200 g kg⁻¹ of lipids (lipid source, soy oil) for 90 days. The following data were collected at 0, 45 and 90 days: final weight; length; conditioning factor; hepatosomatic, gonadosomatic and visceral fat indices; total plasma protein; testosterone; 17ß‐estradiol; free amino acids; and ovary and muscle fatty acid profiles. Additionally, fecundity, oocyte production, egg morphometric parameters, and larval and postlarval growth were evaluated. Results were not statistically different for husbandry and biochemical parameters, but visceral fat content increased with increase in dietary lipid levels. The fatty acid profiles and composition differed among dietary treatments. The egg diameter and area were significantly low in fish fed the 200 g kg⁻¹ lipid diet, thereby hindering growth, survival and weight compared to those in postlarval fish (P < 0.05). The best reproductive rates were obtained when using diets containing 80–140 g kg⁻¹ total lipids.     

Effects of egg aging on the metabolites of ovarian fluid in rainbow trout,Oncorhynchus mykiss

Nuclear magnetic resonance ‐based metabolomics was applied to study effects of egg aging on ovarian fluid metabolites in rainbow trout, Oncorhynchus mykiss. The eggs of three females were pooled and then assigned to three plastic vials for 18 days in vitro storage at 4°C. Ovarian fluid samples were taken 0, 6, 12 and 18 days after storage. Three groups of metabolites including amino acids, osmolytes and energy metabolites were found to change during storage period. The glucose levels of ovarian fluid showed significant decreases on days 12 and 18 after storage (p < .05). For acetoacetate and acetate, significant increases were observed, respectively, on days 12 and 18 after storage (p < .05). The creatine levels of ovarian fluid increased significantly on days 12 and 18 after storage (p < .05). Lactate levels in ovarian fluid elevated during storage period (p < .05). Glycerol levels showed a significant increase on days 12 and 18 after storage (p < .05). The values of osmolytes in ovarian fluid (e.g., betaine, taurine, trimethylamine‐N‐oxide, N,N‐dimethylglycine) showed a decreasing trend on day 12 which continued until the end of storage on day 18 (p < .05). Almost all amino acids elevated on days 12 and 18 after storage (p < .05). After an apparent elevation in isoleucine levels on days 6 and 12, this amino acid decreased on day 18 after storage (p < .05). The osmolytes might act as antioxidant against free‐radicals produced as a result of over‐ripening. Glucose can be used as energy resource for eggs and bacteria during ova storage. Also, change pattern of amino acids indicate hydrolysis of proteins as the time of storage increases.     

Effects of rearing density on growth,fatty acid profile and bioremediation ability of polychaete Nereis diversicolor in an integrated aquaculture system with rainbow trout (Oncorhynchus mykiss)

The objective of this study was to assess the effects of rearing density on the growth and fatty acid profile of Nereis diversicolor and on its capability to bioremediate wastewater in an integrated culture system with rainbow trout (Oncorhynchus mykiss). To this end, a batch of juvenile N. diversicolor (0.03 ± 0.01 mg) was assigned into four different densities (T₁ = 250, T₂ = 500, T₃ = 1,000, T₄ = 2,000, besides T₀ = with no worm) in three replicates. The worm groups were fed with solid waste that was supplied from tanks containing rainbow trout (107.17 ± 13.5 g; 1.39 ± 0.18 kg/m³). During the experiment (60 days), the water temperature was 17.71 ± 0.6°C. The results revealed that SR%, SGR% and WG% of N. diversicolor in T₁ were significantly higher than those of T₂, T₃ and T₄. Both FER rate and biomass gain in T₄ were significantly higher than those in the other groups. The highest removal rate of NO₂‐N (73.72%), NH₃‐N (65.70%), PO₄‐P (59.32%), BOD₅ (69.60%) and TSS (82.33%) were observed in T₄. The major fatty acids presents were palmitic acid, oleic acid, linoleic acid, stearic acid and alpha‐linolenic acid in all worm‐treated groups, with no difference observed in the concentration of these fatty acids among them. Taken together, these findings suggest that organic wastes from rainbow trout farms could be recycled to achieve a sustainable aquaculture goal, and demonstrate that a high percentage of fatty acids in fish feed is not absorbed by rainbow trout but is done by N. diversicolor.     

The effects of sperm–egg ratios on polyspermy in the blood clam,Tegillarca granosa

Polyspermy in Tegillarca granosa, which leads to failure or abnormal development of early embryos, appears to be directly related to varying sperm–egg ratios. We investigated the correlation between sperm–egg ratios and conditions of embryonic development by setting six strict sperm–egg ratios and subsequently scoring fertilization rate, abnormal rate, rates of trochophore and D‐shaped larvae. When sperm–egg ratios rose from 2 × 10²:1 to 1 × 10³:1, D‐shaped larvae rate dropped significantly from 78.8 ± 13.3% to 47.8 ± 14.9% (analysis of variance, P< 0.05), and to 3.6 ± 2.8% in the 2 × 10⁴:1 group. Using fluorescence microscope observation, polyspermy rates rose from 2.6 ± 0.8% to 72.9 ± 4.8% with increases in sperm–egg ratios. Sperm–egg ratios were therefore correlated with polyspermy rate, which seriously affected larval survival. Under the premise of higher fertilization rate, the sperm–egg ratios of ≤2 × 10²:1 appeared to be more beneficial for embryonic development of T. granosa.     

Characterizing egg quality and larval performance from captive mahi‐mahi Coryphaena hippurus (Linnaeus, 1758) spawns over time

Mahi‐mahi Coryphaena hippurus is a promising species for aquaculture development and has been used as a model species for oil toxicology and physiology studies. This species has one of the fastest growth rates of any marine teleost and a unique reproductive biology due to its high spawning frequency and reproductive energy allocation. These characteristics lend the species to being an excellent model for understanding broodstock nutrition for other high energetic pelagic species. In this study, egg morphometrics and larval survival were tracked over a 10‐week period from the initial capture of wild mahi‐mahi broodstock. Larval quality from subsequent spawns collected over time was quantified using larval survival activity indices (SAIs) as a metric to assess egg quality. Larval SAIs were maintained and did not significantly decrease (p < .05) over the time course of this study. A multiple linear regression based on the elapsed time in captivity of the broodstock, egg diameter and larval SAI at 1 dph provided the most accurate prediction of larval SAI at 3 dph (R² = 0.996 p < .05). There were strong positive correlations with larval SAIs at 1 and 3 dph and the key nutrients: eicosapentaenoic acid (C20: 5n‐3, EPA) and related fatty acid ratios, vitamin E and nearly all amino acids under investigation. This study demonstrated that larval survival was maintained over time due to the supply of these key nutrients in the broodstock diet.