Adaptation and potential culture of wild Amphipods and Mysids as potential live feed in aquaculture: a review.

Live foods such as phytoplankton and zooplankton are essential food sources in aquaculture. Due to their small size, they are suitable for newly hatched larvae. Artemia and rotifer are commonly used live feeds in aquaculture; each feed has a limited dietary value, which is unsuitable for all cultured species. Whereas, copepod and cladocerans species exhibit favorable characteristics that make them viable candidates as sources of essential nutrients for hatchery operations. Due to their jerking movements, it stimulates the feeding response of fish larvae, and their various sizes make them suitable for any fish and crustacean. Even though Artemia is the best live feed due to its proficient nutritional quality, the cost is very expensive, which is about half of the production cost. A recent study suggests the use of amphipods and mysids as alternative live feeds in aquaculture. High nutritional value is present in amphipods and mysids, especially proteins, lipids, and essential fatty acids that are required by fish larvae during early development. Amphipods and mysids are considered abundant in the aquatic ecosystem and have been used by researchers in water toxicity studies. However, the culture of amphipods and mysids has been poorly studied. There is only a small-scale culture under laboratory conditions for scientific research that has been performed. Thus, further research is required to find a way to improve the mass culture of amphipods and mysids that can benefit the aquaculture industry. This review article is intended to provide the available information on amphipods and mysids, including reproductive biology, culture method, nutritional value, feed enhancement, and the importance of them as potential live feed in aquaculture. This article is useful as a guideline for researchers, hatchery operators, and farmers.

Morinda citrifolia fruit extract enhances the resistance of Penaeus vannamei to Vibrio parahaemolyticus infection.

Vibrio parahaemolyticus is a gram-negative facultative anaerobic bacterium implicated as the causative agent of several shrimp diseases. As part of the effort to provide biocontrol and cost-effective treatments, this research was designed to elucidate the effect of Morinda citrifolia fruit extract on the immunity of Penaeus vannamei postlarvae (PL) to V. parahaemolyticus. The methanol extract of M. citrifolia was vacuum evaporated, and the bioactive compounds were detected using gas chromatography‒mass spectrometry (GC‒MS). Thereafter, P. vannamei PL diets were supplemented with M. citrifolia at different concentrations (0, 10, 20, 30, 40, and 50 mg/g) and administered for 30 days before 24 h of exposure to the bacterium V. parahaemolyticus. A total of 45 bioactive compounds were detected in the methanol extract of M. citrifolia, with cyclononasiloxane and octadecamethyl being the most abundant. The survival of P. vannamei PLs fed the extract supplement was better than that of the control group (7.1-26.7% survival greater than that of the control group) following V. parahaemolyticus infection. Shrimp fed 50 mg/g M. citrifolia had the highest recorded survival. The activities of digestive and antioxidant enzymes as well as hepatopancreatic cells were significantly reduced, except for those of lipase and hepatopancreatic E-cells, which increased following challenge with V. parahaemolyticus. Histological assessment of the hepatopancreas cells revealed reduced cell degeneration following the administration of the plant extracts (expecially those fed 50 mg/g M. citrifolia) compared to that in the control group. Therefore, the enhanced immunity against V. parahaemolyticus infection in P. vannamei could be associated with the improved hepatopancreas health associated with M. citrifolia fruit extract supplementation.

Salinity tolerance in Clarias gariepinus (Burchell, 1822): insight on blood parameter variations and gill histological changes.

This study was designed to evaluate the tolerance of Clarias gariepinus juveniles to a gradual and abrupt increase in salinity over time. To this effect, C. gariepinus juveniles were exposed to three salinity incremental protocols namely 1 g L-1 day-1, 5 g L-1 day-1, and 10 g L-1 day-1. Changes in the hematological parameters and the gill histology of fish were analyzed to determine the impact of osmotic stress on the health status of the fish and its osmoregulatory ability. The result obtained showed that juveniles of C. gariepinus can tolerate salinity stress up to 14 g L-1. At 15 g L-1 and beyond, all samples died regardless of gradual (i.e., 1 g L-1 day-1 administered for 15 days) or abrupt salinity exposure (i.e., 5 g L-1 day-1 administered for three days and 10 g L-1 day-1 administered for two days). Interestingly, more than 90% of the fish survived a direct 10 g L-1 exposure for 24 h without prior acclimation. The hematological parameters accessed in the fish exposed to 10 g L-1 (either gradually or abruptly) showed a significant increase in the white blood cells and a decrease in the red blood cells, packed cell volume, hemoglobin concentration, and all derived blood parameters. The results of the serum biochemistry show a lower total protein and albumin in the salinity-treated fish compared to the control group. However, the serum glucose and the plasma electrolytes (i.e., K+, Na+, and Cl-) were higher in the former group than in the latter. Aside from the stress response expressed in the blood parameters, severe gill degenerations were seen in the histological micrograph obtained for the salinity-treated fish, while the control had a near-normal gill architecture. It was concluded that C. gariepinus could tolerate salinity exposure of 10 g L-1 day-1 (administered gradually or abruptly) and below without killing the fish within 24 h.

A metagenomic comparison of clearwater, probiotic, and Rapid BFTTM on Pacific whiteleg shrimp, Litopenaeus vannamei cultures.

Biofloc technology improves water quality and promote the growth of beneficial bacteria community in shrimp culture. However, little is known about the bacteria community structure in both water and gut of cultured organisms. To address this, the current study characterised the metagenomes derived from water and shrimp intestine samples of novel Rapid BFTTM with probiotic and clearwater treatments using 16S V4 region and full length 16S sequencing. Bacteria diversity of water and intestine samples of Rapid BFTTM and probiotic treatments were similar. Based on the 16S V4 region, water samples of >20 µm biofloc had the highest abundance of amplicon sequence variant (ASV). However, based on full length 16S, no clear distinction in microbial diversity was observed between water samples and intestine samples. Proteobacteria was the most abundant taxon in all samples based on both 16S V4 and full length 16S sequences. Vibrio was among the highest genus based on 16S V4 region but only full length 16S was able to discern up to species level, with three Vibrios identified-V. harveyi, V. parahaemolyticus and V. vulnificus. Vibrio harveyi being the most abundant species in all treatments. Among water samples, biofloc water samples had the lowest abundance of all three Vibrios, with V. vulnificus was present only in bioflocs of <20 µm. Predicted functional profiles of treatments support the beneficial impacts of probiotic and biofloc inclusion into shrimp culture system. This study highlights the potential displacement of opportunistic pathogens by the usage of biofloc technology (Rapid BFTTM) in shrimp culture.

Effects of Annona muricata Extract on Trypsin, Cathepsin B and Collagenase Activities and Textural Changes in Chilled Macrobrachium rosenbergii.

Texture is an important sensory attribute for overall quality and consumer acceptance of prawns. However, texture is affected during cold storage due to the proteolytic activity of endogenous proteases, resulting in poor quality and a short shelf life. The objective of this study is to determine the inhibitory effects of Annona muricata leaves extract (AMLE) (0, 3, 10 and 20%) on the trypsin, cathepsin B and collagenase activities extracted from the cephalothorax of Macrobrachium rosenbergii. In addition, the textural changes in M. rosenbergii during 20 days of cold storage (4 °C) were also determined. M. rosenbergii were soaked in four different treatments: 0, 3, 10 and 20% AMLE and 1.25% sodium metabisulphate for 10 min at 4 °C. Protease activity was significantly (p < 0.05) reduced at 10 and 20% AMLE. Similarly, cathepsin B showed a significant (p < 0.05) low after treatment at 20% AMLE. The maximum inhibitory activity of trypsin was achieved at 20% AMLE and the standard inhibitor (Tosyl-L-lysyl-chloromethane hydrochloride (TLCK)) compared to the control. Whereas, the lowest collagenase activity was obtained at 20% AMLE compared to the control. These inhibitory effects further maintain the firmness of M. rosenbergii coated with 20% AMLE up to the eighth day of storage when compared to the control. Meanwhile, the highest penetration work was found in the M. rosenbergii coated with 20% AMLE at the twentieth day of storage. In conclusion, treatment at 20% AMLE could be used as a natural preservative to inhibit protease, trypsin and collagenase activity of M. rosenbergii and thus can maintain firmness for up to 8 days of storage.

Heterochely and handedness in the orange mud crab Scylla olivacea: implication for future culture practice optimisation.

Asymmetric body traits in bilateral organisms are common and serve a range of different functions. In crustaceans, specifically among brachyuran crabs, heterochely and handedness in some species are known to aid in behavioural responses such as food acquisition, and sexual and territorial displays. However, the heterochely of the intertidal mud crab genus Scylla is still poorly understood. This study investigated the cheliped morphometric characteristics of orange mud crab Scylla olivacea and the relation of heterochely and handedness to sex. Scylla olivacea is heterochelous, with predominant right-handed (70.2%). Three morphometric variables, i.e., propodus length (PL), propodus depth (PD), and propodus width (PW) were significantly larger in the right cheliped and the estimated handedness based on these three variables were consistent with the presence of molariform teeth. The effect of sex had no influence on the occurrence of heterochely or handedness. The frequency of left-handedness increased with size, especially in males. We postulate that handedness reversal, a phenomenon seen in other crab species when the dominant hand is lost, also occurs in S. olivacea, thereby resulting in a change in left-handedness frequency. The use of chelipeds by males in mate and territorial defenses might provide an explanation for the higher risk of losing a dominant cheliped and thus, higher left-handedness frequency compared to females. Future behavioural research could shed light on the selective forces that affect the handedness distribution in mud crabs. Knowledge on heterochely and handedness of mud crabs could be useful for future development of less aggressive crab populations by claw reversal and the optimisation of limb autotomy techniques.

Assessment on Water Quality Parameter and Nutrients Level of Nyatuh River in Relations with Macrobrachium Rosenbergii Prawn Populations.

In order to determine the safety level of water parameters and nutrients in the natural environment of fish and freshwater prawn in Nyatuh River, Terengganu, Malaysia, it is necessary to conduct an assessment of water quality parameters. Due to its important, a study was conducted to assess the water quality parameter and nutrients contents from Nyatuh River of Setiu Terengganu in relations to the population of freshwater prawn, Macrobrachium rosenbergii caught along the Nyatuh River basin. Total of four expeditions and five stations at different tidal condition for the water quality parameter were assessed during the study. From the results achieved, the overall temperature varied between (26.56°C-29.30°C), dissolved oxygen, DO (3.59 mg/L-6.50 mg/L), pH (4.99-7.01), salinity (0.01ppt-4.22ppt), depth (2.71 m-5.54 m) while for ammonia (0.01 mg/L-0.24 mg/L), nitrite (0.01 mg/L-0.05 mg/L) and phosphate (0.01 mg/L-0.12 mg/L). While the number of prawns caught are 176, 160, 102 and 68 for Expeditions 1, 2, 4 and 3, respectively. Possibly, the heterogeneous number of prawns caught is a result of significant differences in water level depth during high tides and low tides, as well as a fluctuation in the ammonia concentration levels in each of the stations and expeditions. For statistical analysis, the temperature showed no significant difference between the expedition, stations and tidal. That is p = 0.280, p > 0.05 and F = 1.206, respectively. While dissolved oxygen, DO, showed no significant difference as well, that is p = 0.714, p > 0.05 and F = 0.737. However, the level of water depth was significantly different between expedition, station and tidal, that is p = 0.000, p < 0.05 and F = 3.120. Ammonia, on the other hand shows no significant difference between expedition, station and tidal, that is p = 0.476, p > 0.05 and F = 0.973. The same goes for nitrite and phosphate concentration. There was no significant difference between expedition, stations and tidal, that is p = 0.569, p > 0.05 and F = 0.879 and p = 0.247, p > 0.05, F = 1.255, respectively. In Expedition 1, the good water quality parameter and very low ammonia concentration resulted in a larger prawn population as compared to other expeditions. The distribution or mixture of prawns caught is heterogeneous at different stations due to the significant differences in water depth and also to the fluctuation in water quality due to varying ammonia levels. In conclusion, the water quality in Nyatuh River fluctuated across expeditions, stations, and tides, as well as significant differences in water level depths between high and low tides. Due to the rapid growth and importance of industrial and aquaculture operations along the river, extra attention should be devoted to avoid the impact of excessive pollutant in order to protect the ecosystem.

Penilaian parameter kualiti air perlu dijalankan untuk menentukan tahap keselamatan parameter air dan nutrien dalam persekitaran semula jadi ikan dan udang air tawar di Sungai Nyatuh, Terengganu, Malaysia. Maka, satu kajian telah dijalankan untuk menilai parameter kualiti air dan kandungan nutrien di Sungai Nyatuh, Setiu, Terengganu dalam hubungan dengan populasi udang air tawar, Macrobrachium rosenbergii yang ditangkap di sepanjang lembangan Sungai Nyatuh. Sebanyak empat ekspedisi dan lima stesen pada keadaan pasang surut berbeza untuk parameter kualiti air telah dinilai semasa kajian dijalankan. Berdasarkan keputusan yang dicapai, suhu keseluruhan berbeza-beza antara (26.56°C­29.30°C), oksigen terlarut (3.59 mg/L­6.50 mg/L), pH (4.99­7.01), kadar kemasinan (0.01ppt­4.22ppt), kedalaman (2.71 m­5.54 m) sementara bagi ammonia (0.01 mg/L­0.24 mg/L), nitrit (0.01 mg/L­0.05 mg/L) dan fosfat (0.01 mg/L­0.12 mg/L). Manakala bilangan udang yang ditangkap adalah 176, 160, 102 and 68 ekor, masing-masing untuk Ekspedisi 1, 2, 4 dan 3. Bilangan heterogen udang yang ditangkap berkemungkinan adalah hasil daripada perbezaan ketara dalam kedalaman paras air semasa air pasang dan air surut, serta turun naik paras kepekatan ammonia di setiap stesen dan ekspedisi. Bagi analisis statistik, suhu tidak menunjukkan perbezaan yang signifikan antara ekspedisi, stesen dan pasang surut, iaitu p = 0.280, p > 0.05 dan F = 1.206, masing-masing. Oksigen terlarut juga tidak menunjukkan perbezaan yang signifikan, iaitu p = 0.714, p > 0.05 dan F = 0.737. Walau bagaimanapun, paras kedalaman air adalah berbeza secara signifikan antara ekspedisi, stesen dan pasang surut, iaitu p = 0.000, p < 0.05 dan F = 3.120. Ammonia pula tidak menunjukkan perbezaan yang signifikan antara ekspedisi, stesen dan pasang surut, iaitu p = 0.476, p > 0.05 dan F = 0.973. Begitu juga dengan kepekatan nitrit dan fosfat. Tidak terdapat perbezaan yang signifikan di antara ekspedisi, stesen dan pasang surut, iaitu masing-masing pada p = 0.569, p > 0.05 dan F = 0.879 dan p = 0.247, p > 0.05, F = 1.255. Dalam Ekspedisi 1, parameter kualiti air yang baik dan kepekatan ammonia yang sangat rendah menghasilkan populasi udang yang lebih besar berbanding ekspedisi lain. Taburan atau campuran udang yang ditangkap adalah heterogen di stesen yang berbeza disebabkan oleh perbezaan ketara dalam kedalaman air dan juga turun naik kualiti air akibat paras ammonia yang berbeza-beza. Kesimpulannya, kualiti air di Sungai Nyatuh berubah-ubah merentasi ekspedisi, stesen dan pasang surut, serta perbezaan ketara dalam kedalaman paras air antara air pasang tinggi dan rendah. Disebabkan pertumbuhan pesat dan kepentingan operasi perindustrian dan akuakultur di sepanjang sungai, perhatian tambahan harus ditumpukan untuk mengelakkan kesan pencemar yang berlebihan untuk melindungi ekosistem.

Aquaponics production system: A review of historical perspective, opportunities, and challenges of its adoption.

The aquaponics production system integrates hydroponics and recirculatory aquaculture system for the simultaneous production of plants and fish. At a time, such as the postpandemic era, the aquaponics system represents an efficient green farming and eco-friendly alternative to sustainable agricultural production. In this review, the history and development of the production systems were traced vis-a-vis its pros and cons. Although there has been much dispute about the origin of the system, the numerous records of developmental attempts in history have all led to the current complexity of the systems and their efficiency. Water conservation, improved performance, food security, less pollution, and low energy consumption are some of the advantages identified in the use of aquaponics systems for food production. Challenges to the domestication of the system, however, include moderately high start-up capital, the need for stable electricity to operate the system, nutrient availability, as well as treatment of diseases in the system. Although the aquaponics production system could be a panacea for food security in Africa, modalities for the domestication of this technology are largely not in place, hence the need for some government interventions in this regard.

Evaluation of the Feasibility of Harvest Optimisation of Soft-Shell Mud Crab (Scylla paramamosain) from the Perspective of Nutritional Values.

Soft-shell crabs have attracted consumers' attention due to their unique taste and nutritional value. To evaluate the feasibility of harvest optimisation of soft-shell mud crabs, the proximate composition, mineral composition, and total carotenoid, amino acid, and fatty acid contents of edible parts of male and female soft-shell mud crabs at different moulting stages were determined and compared from a nutritional value perspective. The results showed that the sex and moulting stages could significantly affect the nutritional values of the edible portions of soft-shell crabs. The female or male soft-shell crabs in the postmoult Ⅰ stage had a much richer mineral element content than that in other moulting stages. The total carotenoid content in female soft-shell crabs was significantly higher than that in male crabs in all moulting stages, while male soft-shell crabs had better performance in amino acid nutrition than female soft-shell crabs. Moreover, it was found that soft-shell crabs in the postmoult Ⅱ stage had significantly higher contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), while significantly lower contents of saturated fatty acids (SFA) than those in other stages. The present study will provide a reference basis for the diversified cultivation of soft-shell crabs, and further promote the development of the mud crab industry.

Full-Length Transcriptome Reconstruction Reveals the Genetic Mechanisms of Eyestalk Displacement and Its Potential Implications on the Interspecific Hybrid Crab (Scylla serrata ♀ × S. paramamosain ♂).

The lack of high-quality juvenile crabs is the greatest impediment to the growth of the mud crab (Scylla paramamosain) industry. To obtain high-quality hybrid offspring, a novel hybrid mud crab (S. serrata ♀ × S. paramamosain ♂) was successfully produced in our previous study. Meanwhile, an interesting phenomenon was discovered, that some first-generation (F1) hybrid offspring's eyestalks were displaced during the crablet stage I. To uncover the genetic mechanism underlying eyestalk displacement and its potential implications, both single-molecule real-time (SMRT) and Illumina RNA sequencing were implemented. Using a two-step collapsing strategy, three high-quality reconstructed transcriptomes were obtained from purebred mud crabs (S. paramamosain) with normal eyestalks (SPA), hybrid crabs with normal eyestalks (NH), and hybrid crabs with displaced eyestalks (DH). In total, 37 significantly differential alternative splicing (DAS) events (17 up-regulated and 20 down-regulated) and 1475 significantly differential expressed transcripts (DETs) (492 up-regulated and 983 down-regulated) were detected in DH. The most significant DAS events and DETs were annotated as being endoplasmic reticulum chaperone BiP and leucine-rich repeat protein lrrA-like isoform X2. In addition, the top ten significant GO terms were related to the cuticle or chitin. Overall, high-quality reconstructed transcriptomes were obtained for the novel interspecific hybrid crab and provided valuable insights into the genetic mechanisms of eyestalk displacement in mud crab (Scylla spp.) crossbreeding.

Gonad Quality of Banana Shrimp Male Broodstock Penaeus merguiensis (De Man, 1888) Fed Different Natural Diets.

A study was carried out to determine the maturation period, quality and quantity of sperms production in Banana shrimp male broodstock, Penaeus merguiensis fed different natural diets. The three different natural diets namely; squid, fish and shrimp flesh used in this study were obtained from known sources and fed to the tested shrimp in triplicate groups. Based on the results obtained, squid seem to be the most effective natural diet as it enhances the sperms maturation within 20 days. Feeding fish and shrimp flesh as diets for the Banana shrimp broodstock resulted in the observation of maturation in 22 and 24 days, respectively. Similarly, squid diet also recorded the highest (p = 0.002; p < 0.05) sperms count (58.6 to 74.5) as compared to fish diet (44.0 to 61.3) or shrimp diet (28.0 to 42.8). Also, feeding squid diet resulted in a higher percentage of live sperms with ranged between 97.75% to 98.80%. On the other hand, broodstocks fed fish and squid flesh was observed with ranges of between 96% to 97.86% and 92.54% to 96.06%, respectively. It was therefore concluded that squid diet was most effective to improve sperm quality, quantity and maturation period in male broodstock of P. merguiensis. Further study should be carried on the reproductive performance of broodstock fed with squid as diets and it effect on the performances of post larvae obtained.

Fine sand facilitates egg extrusion and improves reproductive output in female mud crab genus Scylla.

Mud crabs (genus Scylla) are gaining attention as potential aquaculture species due to their lucrative market price and high demand. One of the essential components of mud crab culture is broodstock quality. The optimisation of mud crab broodstock culture currently focused on its nutritional aspects and common rearing parameters, including stocking density and temperature. The use of sandy substrate to induce egg extrusion in female Scylla broodstock is common; however, its optimisation has never been conducted. This study investigated (1) the substrate association of two Scylla species (S. olivacea, S. paramamosain) during broodstock conditioning until egg extrusion when the choices of fine (66.99 ± 14.48 µm) and coarse (656.17 ± 38.13 µm) sands were given; (2) the female reproductive output when S. olivacea females were individually exposed to either fine sand, coarse sand, or no sand treatments. Females, spawners and non-spawners, of S. olivacea and S. paramamosain were associated with fine sand and none was observed to bury in the coarse sand tray. The occurrence of egg extrusion was not significantly different between species but moderately associated with the duration of visits (stayed in sand for 1 d, 2 d, ≥3 d). The final incubation period in the sand tray was more than 2 days in all cases, except for one female S. paramamosain (buried in the sand for 1 day prior to egg extrusion). When no choice was available, the highest percentage (58.3%) of females extruded eggs in fine sand treatment, followed by coarse sand treatment (33.3%), and no sand treatment (8.3%). Sand type influenced the weight of egg clutch, total egg number, fecundity, and clutch size. These results suggest that fine sand (<70 µm) substrate should be incorporated into Scylla broodstock rearing to maximise female reproductive output.

Histology and External Morphological Assessment on Ovarian Maturation Stages of Wild Female Banana Shrimp, Penaeus merguiensis (de Man, 1888) for Broodstock Selection Purpose.

Study on ovarian maturation stages were carried out using external morphological assessment of ovarian colourations and histological assessment of Oocyte structure for broodstock selection purpose. Stage 1 to Stage 4 of female shrimps broodstock were sampled from Kuala Muda, Kedah, Malaysia. Four obvious colourations of ovary stages were identified which are: yellow (Stage 1), green yellowish (Stage 2), light greenish (Stage 3) and dark green (Stage 4) through the morphological assessment. The Gonadosomatic Index (GSI) showed significant increment as the gonad reach advance stages. Histological assessment of Stage 1 ovary identified perinucleolar oocyte (PO) with small size oocytes. Stage 2 ovary was identified with yolkless oocyte (YO), Stage 3 ovary was identified with late stage of yolky globules and Stage 4 ovary was identified with fully yolky globules. From the results achieved, it can be concluded that the ovarian colourations and GSI can be applied to identify the ovarian maturation stages, meanwhile, the histology assessment is the most precise method to determine the ovarian maturation stages in more details and accurate for each of the ovarian maturation stages.

Kajian mengenai peringkat kematangan ovari telah dijalankan menggunakan penilaian morfologi luaran pewarnaan ovari dan penilaian histologi struktur oosit untuk tujuan pemilihan induk. Peringkat 1 hingga Peringkat 4 induk udang betina telah diambil sampel dari Kuala Muda, Kedah, Malaysia. Empat warna jelas peringkat ovari telah dikenal pasti iaitu: kuning (Peringkat 1), hijau kekuningan (Peringkat 2), hijau muda (Peringkat 3) dan hijau gelap (Peringkat 4) melalui penilaian morfologi. Indeks Gonadosomatic (GSI) menunjukkan peningkatan yang ketara apabila gonad mencapai peringkat lebih tinggi. Penilaian histologi ovari Peringkat 1 mengenal pasti perinucleolar oocyte (PO) dengan oosit saiz kecil. Ovari Peringkat 2 telah dikenal pasti dengan yolkless oocyte (YO), ovari Peringkat 3 telah dikenal pasti dengan peringkat akhir globul kuning dan ovari Peringkat 4 telah dikenal pasti dengan globul kuning sepenuhnya. Dari keputusan yang dicapai, dapat disimpulkan bahawa pewarnaan ovari dan GSI boleh digunakan untuk mengenal pasti peringkat kematangan ovari, sementara itu, penilaian histologi merupakan kaedah yang paling tepat untuk menentukan peringkat kematangan ovari dengan lebih terperinci dan tepat untuk setiap peringkat.

Whole-transcriptome RNA sequencing revealed the roles of chitin-related genes in the eyestalk abnormality of a novel mud crab hybrid (Scylla serrata ♀ × S. paramamosain ♂).

Chitin is a kind of insoluble structural polysaccharide and plays different roles in different species. In crustaceans, it forms the structural components in the exoskeleton. In our previous studies, novel mud crab hybrids have been produced from the interspecific hybridization of Scylla serrata ♀ × S. paramamosain ♂. Some of the hybrid crabs have been found to be morphologically (eyestalk) abnormal, but the genetic mechanism remains unknown. To address this question, we performed whole-transcriptome RNA sequencing on the control group (normal hybrids), abnormal hybrids, and S. paramamosain to uncover the genetic basis underlying this morphological abnormality. A total of 695 mRNAs, 10 miRNAs, 44 circRNAs, and 1957 lncRNAs were differentially expressed between normal and abnormal hybrids. Several differentially expressed genes (DEGs) associated with chitin and cuticle metabolism were identified, including chitin synthase, chitinase, chitin deacetylase, ß-N-acetylglucosaminidase, ß-1,4-endoglucanase, N-alpha-acetyltransferase, cuticle proprotein, early cuticle protein, and arthrodial cuticle protein. Functional analysis showed that DE miRNAs, DE circRNAs, DE lncRNAs, and lncRNA/circRNA-miRNA-mRNA network were enriched in pathways related to the amino acid, carbohydrate, and glycogen metabolism. Considering the importance of the chitin and cuticle in exoskeleton formation, it can be concluded that the changes in the chitin and cuticle biosynthesis might have caused the eyestalk abnormality in hybrid crabs. These findings can lay the solid foundation for a better understanding of the important roles of chitin and cuticle related genes and the development of hybridization techniques in crustaceans.

Effects of Annona muricata extraction on inhibition of polyphenoloxidase and microbiology quality of Macrobrachium rosenbergii.

Giant freshwater prawn (Macrobrachium rosenbergii) is one of the important aquaculture species and quickly expanding in many countries. High demand and mass commercialization on M. rosenbergii regulating 18% of the international seafood business. Seafood products contend with various level across the supply chains and time to reach the consumers depending upon the marketing and delivery channels after harvesting. Therefore, these may cause biodeterioration such as melanosis (dark pigmentation) and microbial changes that limit the shelf life. This studies reveal the antioxidant properties from Annona muricata leaves extract and their effectiveness in inhibiting the polyphenoloxidase (PPO) activity and delaying the bacterial accumulation during 20 days of chilled storage. Five metabolites including coumarins, flavonoid, glycoside, terpenoids and steroid compound were found in A. muricata leaves extract. Total phenolic content and total flavonoid content of A. muricata were recorded at 191.24 ± 0.03 mgGAEg-1 and 1777.48 ± 1.08 mgQEg-1, respectively. Sixteen percent (16%) of A. muricata leaf extract effectively inhibit 82.41% PPO. Furthermore, 15% of A. muricata leaves extracts showed a significant reduced (p < 0.05) in total bacteria count during 20 days of chilled storage of M. rosenbergii. These conclude that the present of listed secondary metabolites and at approximately ~ 15-16% of A. muricata leaves extracts were effectively inhibiting the melanosis and prolong the shelf life for up to 8 days of M. rosenbergii stored at chilled condition. Therefore, A. muricata leaves extract is potential used as natural preservative agent in obtaining high quality seafood products.

Microalgal Preference and Feeding Density of Selected Microalgae Diets by Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758).

<b>Background and Objectives:</b> Blue swimming crab, <i>Portunus pelagicus</i> (Linnaeus, 1758) are economically important sources of soft-shell products for export demand. However, increasing over-exploitation and pollution towards the sea resources affected the production of the <i>P. pelagicus</i>. The study aimed to determine the microalgal preference and feeding density of the monospecific (<i>Nannochloropsis oculata</i>, <i>Chlorella vulgaris</i>, <i>Isochrysis galbana</i> and <i>Chaetoceros wighamii </i>) by individual <i>P. pelagicus </i>larvae. <b>Materials and Methods:</b> In the microalgal preference study, one polystyrene tray with 100 holes was set up in the experimental tank (200 L) to place the 50 mL centrifuges tube. For feeding density study, the survival rate, Specific Growth Rate (SGR), Body Weight (BW) and Larvae Stage Index (LSI) of each larvae stage were collected from Zoea 1 (Z₁) till megalopa. <b>Results:</b> Results for mean microalgal preference of individual larvae preferred most <i>Chlorella vulgaris</i> during Zoea 1 and 2, the larvae consumed the highest of <i>Nannochloropsis</i> <i>oculata</i>. For Zoea 3 and 4, the highest preference is <i>Isochrysis galbana</i>. For feeding regime, Zoea 1, larvae fed rotifer, <i>Artemia</i> and <i>Chlorella vulgaris</i> (T₃), was the highest survival rate, Zoea 2 was larvae fed rotifer, <i>Artemia</i> and <i>Nannochloropsis oculata</i> (T₅) and both Zoea 3 and Zoea 4, larvae fed rotifer, <i>Artemia</i> and <i>Isochrysis galbana</i> (T₄) was the highest survival rate. The highest SGR and LSI were obtained in T₄ cultured in 14 days. <b>Conclusion:</b> In conclusion, the microalgal preference and feeding density of the selected microalgae are different depending on each larvae stage.

Evidence of Sex Differentiation Based on Morphological Traits During the Early Development Stage of Mud Crab Scylla paramamosain.

In order to uncover the sexual difference in morphology and how early they appear during the development stage of mud crab Scylla paramamosain, we measured, observed, and biostatistically analyzed morphological traits related to sex. For unveiling the morphological differences between sexes, morphological traits involving abdomen width (AW), carapace length (CL), and carapace width (CW) were first measured during the crablet development stage of S. paramamosain in the present study. The correlation analyses and path analyses exhibited that sexual dimorphism in the third abdomen width (AW3) and fourth abdomen width (AW4) could be used for sex identification from stage C VI (stage VI of crablet). Based on the stepwise discriminant analysis and standardized traits, a sex discriminant equation was constructed, which is capable for sex identification in crablets from stage C VI. Observations for secondary sexual traits and abdomen morphology (shape and pleopods) using a dissecting microscope or scanning electron microscope indicated that sexes are easily identified at stage C VIII according to the abdomen shape; meanwhile, at stage C II based on pleopod difference, and at stage C I by the presence or absence of gonopores. The findings in this study contribute greatly to the accuracy of sex identification of S. paramamosain during the early development stage, which promotes the understanding of the morphological differentiation mechanism of sex.

A Review of the Nursery Culture of Mud Crabs, Genus Scylla: Current Progress and Future Directions.

The nursery stages of mud crab, genus Scylla, proceed from the megalopa stage to crablet instar stages. We review the definition and several of the key stages in mud crab nursery activities. The practice of the direct stocking of megalopa into ponds is not recommended due to their sensitivity. Instead, nursery rearing is needed to grow-out mud crabs of a larger size before pond stocking. Individual nursery rearing results in a higher survival rate at the expense of growth and a more complicated maintenance process compared with communal rearing. The nursery of mud crabs can be done both indoors or outdoors with adequate shelter and feed required to obtain a good survival percentage and growth performance. Artemia nauplii are still irreplaceable as nursery feed, particularly at the megalopa stage, while the survival rate may be improved if live feed is combined with artificial feed such as microbound diet formulations. Water quality parameters, identical to those proposed in tiger shrimp cultures, can be implemented in mud crab rearing. The transportation of crablets between different locations can be done with or without water. The provision of monosex seeds from mud crab hatcheries is expected to become commonplace, increasing seed price and thus improving the income of farmers. Numerous aspects of a mud crab nursery including nutrition; feeding strategies; understanding their behaviour, i.e., cannibalism; control of environmental factors and practical rearing techniques still need further improvement.

Use of Pelleted Diets in Commercially Farmed Decapods during Juvenile Stages: A Review.

The increasing market demand for decapods has led to a considerable interest in cultivating decapod species at a larger scale. Following the development of hatchery technologies, most research has focused on the development of formulated feeds for commercially farmed decapods once they enter the juvenile stages. The use of formulated feed for decapods at a commercial scale is still in the early stages. This is probably because of the unique feeding behavior that decapods possess: being robust, slow feeders and bottom dwellers, their feeding preferences change during the transition from pelagic larvae to benthic juveniles as their digestive systems develop and become more complex. The current practice of decapod aquaculture involves the provision of juveniles with food such as natural diet, live feed, and formulated feed. Knowledge of nutrient requirements enables diets to be better formulated. By manipulating the levels of proteins and lipids, a formulated feed can be expected to lead to optimal growth in decapods. At the same time, the pellet's physical characteristics are important factors to be considered upon formulating commercially farmed decapod feeds, considering the unique feeding behavior of the decapod. However, most published studies on decapod nutrition lack data on the physical characteristics of the feed types. Thus, it is difficult to establish a standard feed formulation that focuses on the physical pellet properties. Moreover, careful consideration must be given to the feeding behavior of species, as decapods are known as bottom feeders and are robust in terms of handling feed. Information on the pellet forms, diet composition, and unique feeding behaviors in commercially farmed decapods is gathered to suggest potential better formulated diets that can optimize growth and reproduction. Thus, the purpose of this review is to summarize the information that has been published to date and to come up with suggestions on ways to improve the feed formulation in decapods that comply with their feeding behavior and nutrient requirements. Further research is needed to explore the potential of the pelleted feed at the adult stage so the decapod can take full advantage of the nutrients present in the pellets.

Identification of Sex-Related Genes from the Three-Spot Swimming Crab Portunus sanguinolentus and Comparative Analysis with the Crucifix Crab Charybdis feriatus.

Crabs within the family Portunidae are important marine species in both aquaculture and fishery sectors. The current aquaculture status of most portunids, however, still relies on wild-caught fisheries due to the lack of essential knowledge regarding their reproductive biology and underlying governing mechanism. With the advancement of sequencing technology, transcriptome sequencing has been progressively used to understand various physiological processes, especially on non-model organisms. In the present study, we compared the differentially expressed genes (DEGs) between sexes of Portunus sanguinolentus based on their gonadal transcriptome profiles and subsequently contrasted them with the gonadal DEGs of Charybdis feriatus, the other member of Family Portunidae. In total, 40,964 DEGs between ovaries and testes were uncovered, with 27,578 up- and 13,386 down-regulated in females. Among those, some sex-related DEGs were identified, including a dmrt-like (DMRT) gene which was specifically expressed in males. C. feriatus has approximately 63.5% of genes common with P. sanguinolentus, with 62.6% showing similar expression patterns. Interestingly, the DMRT gene was specifically expressed in male P. sanguinolentus while its homologous gene-doublesex (DSX)-was specifically expressed in male C. feriatus. The DEGs obtained from the gonadal transcriptome of P. sanguinolentus are a beneficial resource for future genetic and genomic research in P. sanguinolentus and its close species. The transcriptomic comparison analysis might provide references for better understanding the sex determination and differentiation mechanisms among portunids.