Broodstock Development Research Articles

The Effect of Stress on the Skin Welfare of Lumpfish (Cyclopterus lumpus Linnaeus, 1758) Broodstock

The aim of this study was to build on the work already conducted in optimising lumpfish broodstock temperature, photoperiod and nutrition by providing vital information on the stress relationship between mucosal barrier functions and the sexual development of lumpfish broodstock. From a population of approx. 300 fish of 1587 g (SEM ± 704 g), a sub-population of 20 fish was injected with 30 mg/kg fish cortisol implants on 5 January 2018. The control group was not treated with implants. The stress-induced cortisol implant group showed elevated plasma cortisol over a period of approximately one month. Analyses of mucus cell area and density suggested that induced stress could produce a positive functional response (stimulus) in lumpfish early in the experiment through a gentle increase in the barrier strength of the skin, reduced mucus cell size and increased density of mucous cells, resulting in a strengthening of the respiratory capacity of the gills. Mucous cell density and calculated barrier strength in the skin were significantly negatively correlated with plasma cortisol, while in the gill filaments of females, there was a significant negative correlation between mucous cell density and oestrogen levels. The reduced density of “empty” cells (Q cells) after stress induction indicates that these cells are important for the maintenance of homeostasis (physiological equilibrium). The fish in this experiment were considered more robust compared to previous analyses on smaller lumpfish.

Positive effects of a mixture of fish oil and soybean oil as a dietary lipid source on the ovarian development and health of female giant river prawn, Macrobrachium rosenbergii broodstock

Lipids are key nutrients that affect the development of the ovary in aquatic animals. This study aimed to investigate the effects of different lipid sources on the ovarian development and health of Macrobrachium rosenbergii broodstock. The M. rosenbergii broodstock, with an initial body weight of 8.07±0.74 g, were fed diets containing 5 % fish oil (FO), soya bean oil (SO), rapeseed oil (RO), coconut oil (CO), and a 1:1 mixture of fish oil and soybean oil (MO) as lipid sources for a period of 56 days. The results indicated that there were no significant differences in survival rate (SR) and hepatopancreatic index (HSI) among the different groups (P > 0.05). However, the specific growth rate (SGR) and gonadosomatic index (GSI) in the MO group were significantly higher than other groups (P < 0.05). Additionally, fatty acid levels in diets directly influenced the fatty acid composition of prawn hepatopancreas, showing a similar trend to that observed in the diet itself. Furthermore, compared to the other trial groups, haemolymph levels of 17-β estradiol (E2) and progesterone (PROG) were significantly increased in the MO group (P < 0.05). The ovarian section also exhibited better histomorphology and larger oocyte diameter in this group. Moreover, total antioxidant capacity was significantly increased in the MO group (P < 0.05). Saturated fatty acids in RO and CO groups could promote the expression of lipid synthesis-related genes fatty acid synthase (fas) and acetyl-CoA carboxylase (acc), concurrently suppressing the expression of lipid catabolism-related genes acyl-CoA oxidase-1 (acox-1) and AMP-activated protein kinase alpha (ampkα) (P < 0.05). Conversely, polyunsaturated fatty acids in the MO group significantly up-regulated the expression levels of fatty acid binding protein-3 (fabp-3) and peroxisome proliferator-activated receptor gamma (pparγ) (P < 0.05). Based on the findings of hepatopancreatic tissue structure, it was determined that the use of a single vegetable oil resulted in some damage to the hepatopancreatic tissue structure of M. rosenbergii broodstock, leading to increased oxidative stress. In conclusion, it is recommended that a 1:1 mixture of fish oil and soybean oil be used as a dietary lipid source to effectively meet the nutritional requirements during the ovarian development period of M. rosenbergii broodstock. This combination also enhances antioxidant properties, promotes the synthesis of haemolymph steroid hormones and lipid metabolism in female prawns, thereby facilitating ovarian development and overall health of M. rosenbergii broodstock.

Effects of dietary cholesterol on ovary development and reproductive capacity in Pacific white shrimp broodstock, Litopenaeus vannamei

Cholesterol is an important component of fresh biological baits and essential precursor to synthesize steroid hormones for crustacean. However, the cholesterol demand in Pacific white shrimp broodstock and its roles on ovary development and reproductive capacity are unknown. In the present study, female Pacific white shrimp broodstock (initial weight 51.3 ± 0.5 g) were fed with three diets contained 0.5 %, 1 % or 1.5 % cholesterol for 45 days. The results found that dietary cholesterol levels did not affect survival rate, weight gain, egg-laying number, vitellogenin content and vitellogenin receptor gene expression in the hepatopancreas. However, the hepatosomatic index, gonadosomatic index, egg diameter, vitellogenin level in the ovary and fertilized egg, C22:6n-3 (DHA) level in the fertilized egg, total protein, triglyceride and cholesterol contents were all increased in the 1.0 % and 1.5 % cholesterol groups than those in the 0.5 % cholesterol group. Moreover, compared with the 0.5 % and 1.0 % cholesterol groups, the 1.5 % cholesterol group had significantly higher gonad maturation number, mating rate, estradiol level in the hemolymph, steroid hormones synthesis related genes (HMGCR, StAR, 17βHSD and 1vMFBP) expression in the ovary and hepatopancreas. In conclusion, dietary 1.5 % cholesterol could promote ovary development and reproductive capacity in female Litopenaeus vannamei broodstock by improving nutrients accumulation and steroid hormones synthesis pathway. Our results provide guidance for design of artificial compound feed and healthy development of shrimp broodstock farm.

Ameliorative Effects of Different Dietary Levels of Fish Protein Hydrolysate (FPH) on Growth and Reproductive Performance, Feed Stability, Tissues Biochemical Composition, Haematobiochemical Profile, Liver Histology, and Economic Analysis of Pabda (Ompok pabda) Broodstock

This study investigated the impacts of various inclusion levels of dietary potential of fish protein hydrolysate (FPH) on the growth and reproductive performance, biochemical composition, blood parameters, and liver histology of Ompok pabda broodstock. About 600 pabda broods (11.00 ± 0.05 g) were distributed into 12 cages and fed twice in a day. For this, four experimental diets (crude protein: 30%; crude lipid: 9%) were prepared by incorporating FPH at different percentages (0%, 5%, 7%, and 9%). The FPH positively impacted (p&lt;0.05) the durability index, water stability, and swelling rates of the experimental diets. Furthermore, significantly higher palatability (p&lt;0.05) was recorded for pabda diets incorporated with 5% and 7% FPH. After 90 days, the growth performance of pabda in final weight, live weight gain, total biomass, specific growth rate, hepatosomatic index, visceral somatic index, and nutrient utilization indices, feed conversion ratio and protein efficiency ratio, was significantly (p&lt;0.05) improved when fed with 7% FPH diet. Additionally, the ovipositor diameter (5.10 ± 0.05 mm), spawning response (98.48 ± 2.4%), fecundity (13.28 ± 0.23 × 104 eggs/kg), and egg fertilization rate (87.09% ± 0.14%) were significantly higher (p&lt;0.05) for the 7% FPH dietary group than other treatments. The fish group that received control diet experienced a marked (p&lt;0.05) reduction in egg hatching rates, coupled with longer ovulation period as compared to FPH-treated groups. Dietary FPH inclusion at different levels also caused notable improvements (p&lt;0.05) in most hematological and serum biochemical indices of pabda broodfish. The 7% FPH group also exhibited enhanced liver health, characterized by superior nuclei, erythrocyte, and cytoplasmic structure and boosted the farm economics efficiency. In summary, 7% dietary FPH is suitable and beneficial for O. pabda broodstock development in captivity by improving growth and reproductive performance, overall health, and farm economics.

Research and Innovation in Malaysian Mahseer, Tor sp., Broodstock Development Programme

Malaysian Mahseer (Tor spp.) is a highly priced native freshwater fish in Malaysia and much sought after as food, ornamental and recreational fish. However, the production of mahseer is still insignificant. Due to the decline in the wild stock population of mahseer, farmers are compelled to rely heavily on imported broodstock or hatchery-produced fingerlings. The R&amp;D on mahseer is also limited with only several reports on breeding techniques, feed requirement and genetic distance between populations. The availability of superior breeding stocks, efficient hatcheries management and formulation of maturation diet that could expedite the maturation process could greatly assist in increasing mahseer aquaculture productivity. This paper presents the R&amp;D carried out by the Fisheries Research Institute, Department of Fisheries Malaysia starting from the 11th Malaysia Plan (2016 to 2020), particularly on the broodstock development, breeding, disease, seed management, formulation and validation of maturation diet. In this programme, broodstocks obtained from five different states namely Pahang, Johor, Sarawak, Perak and Terengganu, Malaysia were used as a base population and mated using full diallel method to produce a total of 75 families. The maturation diet enhanced the breeding capacity and shortened the maturation period of mahseer from 3.0 years to only 1.8–2.0 years. Three innovations, hatching system, nursing system and maturation diet were produced from this programme were also registered innovations. This paper also deliberates the challenges faced in broodstock development programme and the way forward.

Brood Stock Development, Reproductive Performance and Breeding of African Catfish (Clarias gariepinus) in Pakistan

Brood Stock Development, Reproductive Performance and Breeding of African Catfish (Clarias gariepinus) in Pakistan

Observation of Egg and Larval Quality of Milkfish (Chanos-chanos Forskall) G1 and G0 Broodstock in Controlled Tanks Supports The Development and Cultivation of Milkfish in The Community

Milkfish, a key aquaculture commodity, is vital for industrialization and food security. Obtaining milkfish seeds from nature is challenging, but hatcheries, especially in Buleleng north coast, can produce them in large quantities. However, the varying quality of milkfish eggs has led to a decline in seed quality. Research on G1 and G0 milkfish broodstock development is necessary. The aim is to assess the performance and spawning of G1 and G0 broodstock reared in controlled tanks to aid community cultivation. The study used a descriptive method to evaluate the spawn, eggs, and fry of G0 and G1 broodstock. Results showed that G1 and G0 broodstock have similar spawning and egg quality. G1 broodstock can produce 42,940,000 eggs, with 60-82% fertilization and SAI 2.50-4.12, while G0 can spawn 55,940,000 eggs, with 50-80% fertilization and SAI 2.00-4.40. The G1 derivative’s performance and egg quality are consistent, and the eggs are like the G0 natural broodstock. Milkfish fry production and pond culture cultivation continue to develop in the archipelago.

Effects of dietary squid oil on breeding performance and embryonic and larval development of butter catfish Ompok pabda

The present study was conducted to determine the effects of squid oil on the endangered butter catfish, Ompok pabda to confer enhanced breeding with embryonic and larval development for promoting its aquaculture. A total of 360 fish were obtained from the Brahmaputra River, Mymensingh, Bangladesh, of which, 60 fish stocked in each tank having an initial weight and length of 16.35 ± 0.57 g and 15.25 ± 0.38 cm, respectively, in the cisterns of 1.22 × 2.44 × 1.25 m (total 6 cisterns) maintained at 90 cm water depth. During the experimental period, a constant physico-chemical conditions of water such as temperature, pH, and dissolved oxygen (DO) were 26.5 ± 2 °C, 7.4 ± 0.2, and 6.7 ± 0.5 ppm, respectively, were maintained in each cistern. As the source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), dietary 1 % squid oil (SQO) was supplemented in the diet of the treated group (SQO diet) to compare while the control group offered with basal diet without SQO supplementation (CON diet). The fecundity, spawning, fertilization, hatching rate, and survival rate of fry in SQO group were significantly (P < 0.01) higher than in the CON group. Moreover, better early embryonic and larval development of fish was observed in the SQO group i.e. size of fertilized egg diameter, growth and early developmental stages of larvae but not significantly different from the control group. Collectively, the results of the present study showed that dietary SQO supplementation improved the breeding and reproductive performances of butter catfish. The findings of this study could assist to develop a nutrient-rich diet for the better broodstock development of butter catfish at the farm level which may ultimately reduce the mortality and poor survival of offspring of this commercially important catfish species.

Capture of wild juveniles, growth and spawning of the southwestern Atlantic wreckfish (Polyprion americanus) in Argentina

Wreckfish (Polyprion americanus) is a marine fish of great interest as a new aquaculture species due to its easy adaptation to farming conditions, rapid growth and market price. In the Southwestern Atlantic Ocean, the species forms a genetic stock different from that of the Northern Hemisphere and also to populations of the South Pacific. This study presents the research conducted in Argentina from 2011 to 2020 on the development of a wreckfish broodstock from juvenile specimens. Wreckfish (n = 21) were caught with fishing rods at depth between 18 and 75 m depth, off the coast of Buenos Aires Province, Argentina (37°30′S - 39°00′S). All fish suffered barotrauma, but specimens captured at a depth < 45 m and whose swim bladders were deflated by puncture had a survival rate > 90%. Juvenile wreckfish (n = 12) with an initial body weight of 2–3 kg were kept in a recirculating aquaculture system (RAS) and fed local fish for 36 months. During this on-growing stage, a natural photoperiod regime with reduced light intensity was accompanied by seasonal variations in the RAS's thermal regime (14–19 °C). From then on, a maturity and reproductive protocol was implemented, where the temperature was lowered (12–17 °C) and the diet was complemented with a formulated semi-moist feed. Juvenile wreckfish grew fast, gaining about 2.5 kg in 11 months with a specific growth rate (SGRBW) of 0.2% day−1 and reaching 10–12 kg in 36 months. There was no significant difference in growth performance between sex groups during the on-growing stage. However, from months 36 to 57, the SGRBW of females (0.058 ± 0.008% day−1) was significantly higher than males (0.035 ± 0.005% day−1). After 67 months in captivity, the first natural spawning was achieved in a communal tank with a sex ratio 4 females: 6 males. Two consecutive spawning seasons were analysed, which showed a large daily variation in total number of eggs, percentage of floating eggs (potentially viable eggs) and spawning intervals. A marked improvement in spawning performance was observed from one season to the next. In the first season, a total production of 5.21 million eggs was reached, of which only about 2.7% were floating, while in the second season the values increased to 13.23 million eggs and 32.6%, respectively. We have successfully developed a broodstock of wreckfish capable of achieving natural spawning. Further research is needed to obtain reliable spawning and large production of high-quality eggs.

Broodstock development, induced spawning and larval rearing of the bilih, Mystacoleucus padangensis (Bleeker, 1852), a vulnerable species, and its potential as a new aquaculture candidate.

Background: Mystacoleucus padangensis living in Lake Singkarak, Indonesia, has high potential market demand but is threatened by overfishing and has not been successfully cultured. This study describes the first broodstock development, induced breeding, and larval rearing of M. padangensis. Methods: A total of 1,000 female and 1,000 male broodfish were collected from the wild and reared in two concrete ponds (128 m 2) at the Centre for Biodiversity Conservation, P.T. Semen Padang, Indonesia. The broodfish were fed commercial feed to satiation at 09:00 and 17:00 h. The females (average weight 7.56 ± 0.85 g) and males (4.86 ± 1.20 g) were selected at a ratio of 1:4 (female:male), and gonad maturation was induced with a single dose of GnRH analogue (Ovaprim) of 0.1 ml/fish. At 16 h after hormone injection, eggs were collected individually into a plastic vessel. Spermatozoa were collected with sterile syringes. Eggs were fertilized using the "dry" method, and 0.5 ml samples (equal to 100 eggs) were taken. The eggs were incubated in a plastic strainer with a water volume of 1.57 litres and placed in a tarpaulin pond with a volume of 150.72 litres. Results: The overall hatching rate was 78.93 ± 4.13%. The newly hatched larvae were 3900.81 µm long, with a yolk sac of 82881.480 µm 2. The mouth opened at 72 days post hatching (DPH) with a gape measuring approximately 61.880 µm. The protocol of larval feeding started with artificial feed, followed by Artemia nauplii up to 30 DPH. Weaning of larvae started at 4 DPH. Larvae started metamorphosis by 15 DPH and ended by 22 DPH when the larvae reached 7430.27 µm. Larval rearing resulted in an average survival rate of 28.4 ± 3.04%. Conclusions: Its successful spawning induction and high larval hatching and survival rates make M. padangensis an excellent aquaculture candidate.

Performance of Striped Bass reared at mid‐Atlantic and Gulf coast photothermal regimes

AbstractObjectiveInvestigate Striped Bass Morone saxatilis growth in different photothermal environments and generate an interest in strain‐specific broodstock development for marine net‐pen culture.MethodsIn this effort, Striped Bass strains from Atlantic (Delaware, Virginia, and Maryland) and Gulf Coast (Florida and Texas) states were cultured in recirculating aquaculture systems, simulating a full‐production cycle to early market size in each respective region's photothermal environment. The Atlantic and Gulf strains were initially maintained in recirculating aquaculture systems “nurseries” until 400 and 160 days postspawn, respectively, when offshore conditions (temperature) were conducive for stocking juvenile fish. Individuals from all strains were implanted with PIT tags and stocked (“common garden design”) into a pair of identical recirculating systems (three 5000‐L tanks/system). One system received 48 Atlantic fish/tank (16 fish/strain; Delaware, Virginia, and Maryland), and the second system received 48 Gulf fish/tank (24 fish/strain; Florida and Texas). Salinity was maintained at 30‰, and photothermal regimes corresponded with ambient ocean conditions at selected locations off the mid‐Atlantic and Gulf coasts. Studies were conducted for up to 2 years, and production parameters (feed conversion, absolute growth rate, survival) were compared.ResultThe final weights of ungraded fish in both simulated locations averaged approximately 900 g by 600 days postspawn and early market size (~1.3 kg) by 800 days postspawn.ConclusionGrowth rates differed by strain in both nursery and grow‐out phases, but the results indicate high potential for production of Striped Bass in U.S. coastal waters.

Captive Production of Bagrid Catfish, &lt;i&gt;Rita chrysea&lt;/i&gt; For Species Diversification in India

Catfish farming is getting more popular as an alternative to carp culture in India due to several advantages such as suitable for high-density farming, hardy species, more consumer preference, high market value, less pin-bones and higher economic returns. Catfishes are having a high regional preference and among many catfish species, the Mahanadi rita, Rita chrysea is one among the species having huge consumer preference in Odisha and Chhattisgarh region. The broodstock development, captive breeding, seed production and grow-out culture technology were successfully standardized by ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar. The study findings reveal that R. chrysea attains maturity in 1+ year and the ideal broodstock size of 90 g above is most suitable for induced breeding programme. The species breeds in monsoon season, June-August. The fecundity was found to be 10,000-13,000 per 90-130 g brooder. The fertilization and hatching percent were estimated in the range of 70-90% and 60-80%, respectively. The larval stocking density of 2 to 3 nos per litre of water is found to be ideal stocking density to get higher growth and improved larval survival. The fingerlings can be produced in tank system with the stocking density of 100-150 nos per m2 with the survival of 50-60 % and it reaches about 2-4 g in 2 months rearing period.

Examination of the effects of highly diluted bioactive compounds on gametogenesis in relation to energy budget and oocyte quality in mussel (Modiolus capax) broodstock

A critical bottleneck for bivalve hatcheries is the availability of mature broodstock with high-quality gametes to ensure the production of healthy spat. The use of highly diluted bioactive compounds (HDBC) has emerged as a novel and prophylactic strategy to improve gonad development, reproduction bioenergetics, and oocyte quality of marine bivalve broodstock. This study evaluates the effect of HDBC formulas to enhance the laboratory-controlled breeding capacity of Modiolus capax adult mussel, selected as a model organism because of its aquaculture potential as an alternative seafood resource. The experimental design included three replicates of three HDBC treatments at 31Centesimal (1 × 10−31) dynamizations using distilled water as the final excipient (TR1: SiT, CaS, HeS; TR2: PhA, FeP, ZnP; and TR3: ViP, ViA, ViT), and two control treatments: C+ hydro-alcoholic solution at 1% (Usual HDBC vehicle) and C- (distilled water) during a 30-day period. As a result, TR1 enhanced energy reserves (lipids and carbohydrates) in all tissues; TR2 promoted an increase in lipid and carbohydrate content in the gonad and their transfer into developing oocytes; TR3 significantly improved gonad development and reproductive capacity of the mussels with the highest proliferation of mature oocytes, enhancing food-nutrient assimilation and energetic reserve transfer from the somatic tissues to the ovary. Additionally, all HDBC formulas recorded a lower (P < 0.05) number of atretic oocytes compared to the untreated animals. This evidence reflects a simultaneous improvement of gametogenesis and energy budget of M. capax broodstock, ensuring sexual maturation and higher-quality oocytes when HDBC are used.

Positive effects of optimal dietary cholesterol levels on the ovary development and health of female Pacific white shrimp, Litopenaeus vannamei broodstock

Cholesterol is an important precursor necessary for the synthesis of steroid hormones and other functional substances. This study conducted a 28-day feeding experiment to assess the effects of different levels of dietary cholesterol (0.2%, 0.8%, 1.4%, 2.5%, or 3.2%) on the ovarian development and health status of female Litopenaeus vannamei broodstock (initial weight 39.5 ± 4.3 g). The results showed that dietary supplementation with 1.4% cholesterol can significantly increase the GSI and HSI of shrimp. Meanwhile, the 1.4% cholesterol group significantly increased the antioxidant capacity of shrimp, and increased mRNA expression of transcription factors (FoxO, GST) was also coordinated to regulate the antioxidant system. The TG and T-CHO contents were significantly accumulated in the hepatopancreas of shrimp fed a 1.4% cholesterol diet compared to other treatments. In addition, in the 1.4% group, the concentration of estrogen (E2, PROG, MF) was significantly increased compared to that in the other experimental feed groups. This was achieved by upregulating the mRNA expression of Vg, Vgr, StAR3, 3β-HSD, 17β-HSD, and ERR associated with the steroid hormone synthesis pathway. Correlation analysis of serum metabolomics and ovarian transcriptomics found that differential metabolites and differentially expressed genes were commonly significantly enriched in the glutathione metabolism pathway. Increased GST activity further enhances shrimp antioxidant capacity, which may also promote steroid hormone synthesis. In conclusion, dietary supplementation with 1.4% cholesterol can significantly promote ovarian development and strengthen the antioxidant system of female L. vannamei broodstock. To improve reproductive performance and health status, it is suggested that the appropriate dietary cholesterol supplementation content for female broodstock of L. vannamei is 1.606%–1.680%.

Influence of different feeding rates of polychaete worms, Eulalia viridis (Annelida, Polychaeta), on the gonad development of male Penaeus semisulcatus (Decapoda, Dendrobranchiata) under captive conditions

Abstract Penaeus semisulcatus is a large growing species, attaining a maximum size of about 250 mm in total length. It is more resistant to white spot syndrome virus (WSSV) than other cultivable penaeid shrimps, which makes it a potential candidate for culture. The present study evaluated the influence of a different feeding rate of polychaete worms on the gonad development of male P. semisulcatus under captive conditions. P. semisulcatus sub-adults were obtained in the wild. The shrimps were fed with three different concentrations of polychaete worms, viz., ad libitum (T1), 5% of body weight (BW) (T2) and 10% BW (T3), and fresh sardines were fed as a Control (C) diet, all for a period of 60 days. Sampling was done once in 15 days and the bio-growth parameters were recorded. The gonads were harvested for histological analysis. The maximum weight gain (10.19 g), mean weight gain percentage (85.20%), mean daily growth rate (DGR) (0.169833) and mean specific growth rate (SGR) (0.45) were found in shrimps fed with the polychaete worm diet at 5% BW. The estimated bio-growth parameter values were statistically significant when analysed using One way ANOVA (). Histological sections of the testis showed variations in the development of the gonad between the treatments with different feeding rates during the 60 days trials. Indeed in all aspects, the development was higher in shrimps fed with polychaete worms at 5% BW. It can be concluded that feeding polychaete worms at 5% BW created a regime able to improve growth rates, gonad maturation, and quality in the development of the captive male brood stock.

Broodstock development, induced spawning and larval rearing of the bilih, Mystacoleucus padangensis (Bleeker, 1852), a vulnerable species, and its potential as a new aquaculture candidate

Background: Mystacoleucus padangensis living in Lake Singkarak, Indonesia, has high potential market demand but is threatened by overfishing and has not been successfully cultured. This study describes the first broodstock development, induced breeding, and larval rearing of M. padangensis. Methods: A total of 1,000 female and 1,000 male broodfish were collected from the wild and reared in two concrete ponds (128 m2) at the Centre for Biodiversity Conservation, P.T. Semen Padang, Indonesia. The broodfish were fed commercial feed to satiation at 09:00 and 17:00 h. The females (average weight 7.56 ± 0.85 g) and males (4.86 ± 1.20 g) were selected at a ratio of 1:4 (female:male), and gonad maturation was induced with a single dose of GnRH analogue (Ovaprim) of 0.1 ml/fish. At 16 h after hormone injection, eggs were collected individually into a plastic vessel. Spermatozoa were collected with sterile syringes. Eggs were fertilized using the "dry" method, and 0.5 ml samples (equal to 100 eggs) were taken. The eggs were incubated in a plastic strainer with a water volume of 1.57 litres and placed in a tarpaulin pond with a volume of 150.72 litres. Results: The overall hatching rate was 78.93 ± 4.13%. The newly hatched larvae were 3900.81 µm long, with a yolk sac of 82881.480 µm2. The mouth opened at 72 DPH with a gape measuring approximately 61.880 µm. The protocol of larval feeding started with artificial feed, followed by Artemia nauplii up to 30 DPH. Weaning of larvae started at 4 DPH. Larvae started metamorphosis by 15 DPH and ended by 22 DPH when the larvae reached 7430.27 µm. Larval rearing resulted in an average survival rate of 28.4 ± 3.04%. Conclusions: Its successful spawning induction and high larval hatching and survival rates make M. padangensis an excellent aquaculture candidate.

Disinfection of Perinereis aibuhitensis eggs with peroxymonosulfate to eliminate covert mortality nodavirus (CMNV)

Perinereis aibuhitensis is an essential bait for prompting ovarian development and sexual maturation in aquaculture shrimp broodstock. It is common for shrimp to become infected with pathogens by ingesting feed containing potential viruses. To prevent P. aibuhitensis being live feeds for shrimp broodstock from transmitting pathogens, we evaluated the disinfection effect of peroxymonosulfate (PMS) against covert mortality nodavirus (CMNV) by carrying out Oryzias melastigma (marine medaka) challenge assay and testing CMNV-exposed P. aibuhitensis eggs. In the marine medaka injected with PMS (15 and 20 ppm (ppm))-inactivated CMNV, no CMNV was detected at 6 and 12 days post-infection (d.p.i.) by using quantitative reverse transcription PCR (RT-qPCR). As well, no CMNV probe positive signal and pathological signs caused by CMNV in these marine medaka were present in situ hybridization (ISH) and histopathology assays. CMNV was not detected in the nectochaeta larvae originated from CMNV-exposed P. aibuhitensis eggs treated with PMS (5, 10, 15 and 20 ppm) for 1 min. In addition, nereids treated with 15 ppm PMS for 1 min had higher hatchability. Even at low concentrations of PMS-treated eggs, the hatchability was higher than that of the no-PMS-treated group, and no adverse effects on larval development after hatching were observed. Our study showed that disinfection of CMNV-exposed eggs by PMS is feasible. Disinfection of P. aibuhitensis eggs with PMS could reduce the risk of transmission of CMNV. Within acceptable limits for hatchery spawn losses, the recommended disinfection dose of PMS is 15 ppm for 1 min. This study laid the foundation for the culture of specific pathogen-free P. aibuhitensis and to provide biological baits with no pathogenic risk to farmed shrimp.

Cryopreservation of sperm in the spotted scat, Scatophagus argus (Linnaeus, 1766) - Conservation and aquaculture perspectives

This study emphasizes the need for sperm quality assessment and cryopreservation strategy in the spotted scat Scatophagus argus as the occurrence of male population of this species is limited. Analyses of sperm quality were made including ionic content and osmolality of seminal plasma and blood serum. Sodium chloride (0.9%) was optimized as the extender with a dilution ratio of 1:3 (milt:cryomedium) for all experiments. Cryoprotectants including dimethyl sulfoxide (DMSO), dimethyl acetamide (DMA), glycerol (GLY), propylene glycol (PG), ethylene glycol (EG) and methanol (MeOH) were screened at various concentrations and equilibration times. Cryopreservation was performed using the cryoprotectants DMSO, GLY, EG, and MeOH individually as well as in combinations. Experiment 1 was done with DMSO, GLY, EG and MeOH (5, 10 and 15%); experiment 2 was done with DMSO (5%) + GLY (5%), DMSO (5%) + EG (5%), DMSO (5%) + MeOH (5%). Simultaneously, experiment 3 was done with both cryoprotectants and co-cryoprotectants viz. DMSO (5%) + egg yolk (5%), DMSO (5%) + coconut water (5%), DMSO (5%) + tomato water (5%) and DMSO (5%) + honey (5%). The cooling sample was optimized and performed with a one-step freezing protocol of −5 °C/min from 25 °C to −150 °C. The results indicated that samples subjected to experiment 2 using DMSO (5%) + EG (5%) for 60 days of storage registered maximum motility (82.33 ± 2.51%), duration time of sperm motility (10.45± 1.01 min) and viability (84.14 ± 5.29%) of post-thaw cryopreserved sperm. Morphology and ultrastructure of post-thaw sperm showed smooth surface topography and normal architecture of cellular organelles. Biochemical analysis indicated a reduction in the protein content of post-thaw cryopreserved sperm. DNA integrity (Comet assay) showed 6.30 ± 1.00% of tail DNA in post-thaw sperm, whereas fresh sperm registered 2.41 ± 1.85%. Functional integrity using the HOST of post-thaw sperm showed a maximum of 82.66 ± 1.15% with DMSO (5%) + EG (5%). Finally, fertility of post-thaw sperm using mature eggs of wild-caught females indicated the entry of sperm by breaking the vitelline membrane. Overall it was demonstrated that the DMSO (5%) + EG (5%) was amenable to the long-term preservation of sperm. Therefore, this protocol can be used as an alternative for male broodstock development under captive breeding program.

Reproductive performance of captive-reared Indian white shrimp, Penaeus indicus, broodstocks over two generations

Closing the complex life cycle of closed thelycum shrimp in captivity is one of the fundamental challenges in breeding programs. In the present study, we investigated the sexual maturity, broodstock development, and spawning performance of two generations of captive-reared Indian white shrimp, Penaeus indicus, over 36 months originated from a single stock of wild brooders. The post larvae (GN-1) produced from wild P. indicus (G0) and P.L. (GN-2) produced from captive-reared (GN-1) broodstocks were nursery (1000 PL m-3) and grow-out (12 shrimp m-2) reared, and subsequently raised in broodstock ponds (1 shrimp m-2). The annual salinity and photoperiod in broodstock ponds varied between 20 to 36 ppt, and 11.2 -12.5 L and 11.5-12.8 D hours, respectively. The light intensity varied between 91 ± 6 lux at dusk to 75,358 ± 1719 lux at noon. The size at first impregnation or mating was 16.45 ± 1.7 g (132 DOC) and 17.62 ± 1.9 g (90 DOC), respectively, in GN-1 and GN-2 females. By 220 DOC, 25% of the GN-1 females initiated gonad development, whereas 55% of the GN-2 females recorded developing ovaries or were in stage II at 150 DOC. The broodstock attained an average final body weight of 38.85 ± 1.5 g (GN-1) and 42.65 ± 1.8 g (GN-2) by 360 DOC. The highest (p&amp;lt;0.01) eggs per gram body weight (5137 ± 303 eggs g-1) and hatchability, H (83 ± 0.7%), was recorded in wild broodstocks (G0) followed by GN-2 (1,715 ± 162 eggs g-1; H: 69 ± 2%) and GN-1 (1,476 ± 151 eggs g-1; H: 75 ± 1%). However, captive-reared broodstock had better survival (89-92%) than wild broodstocks (71 ± 0.8%). Further, indoor maturation trial (21 days) using ablated broodstocks (GN-1) revealed 79% of the impregnated broodstocks undergo molting, resulting in the loss of sperm pack and subsequent reduction in mating efficacy to 29%. The average sperm count and percentage of normal sperm also recorded (p&amp;lt;0.05) reduction during the maturation cycle. The data generated in the present investigation can form the baseline information for developing the breeding strategy for the genetic improvement of Indian white shrimp in India.

Breeding and Hybridization of Clownfish Amphiprion ephippium × Amphiprion melanopus in Captivity

Development of broodstock, spawning, and early rearing of the hybrid clownfish, Amphiprion ephippium (♂) × Amphiprion melanopus (♀), was studied under captive conditions. The fishes were successfully paired after being together for over a year. Spawning occurred between 0700 to 1000 hours every 3 weeks. More than 200 eggs were spawned each time, with an egg size of 1.5 ± 0.5mm. Fertilized eggs turned from bright orange to black to silvery before hatching after being incubated for 7–9 days. Out of 20 batches of eggs spawned, 5 batches were successfully hatched, with only 2 batches surviving to adulthood. The average survival rate for all the batches hatched was 21.16%. Newborn larvae measured about 3–4 mm long, with transparent fins that fused, forming a single fin fold. Larvae underwent metamorphosis on day 10 post hatched, where the fins started to separate, form, and develop body colorations. Two clear and thick bands were observed on the body (head and middle) as early as 14-day post hatched to 90-day post-hatched, where the banding reached its peak. The middle band then began fading as the juveniles grew. By 130-day post-hatched, the juveniles became adults with unique coloration featuring a headband and a black blotch, reaching the maximum size of 34 mm. The hybrid clownfish underwent metamorphosis earlier and reached marketable size much sooner compared to its parent species, making it a suitable candidate for ornamental fish culture. It is the first documentation on the production of hybrid clownfish A. ephippium and A. melanopus both in Malaysia and worldwide.