In the Philippines, salt tolerant Nile tilapia strains have been developed and promoted for culture to increase tilapia production in brackishwater pond systems previously dedicated for milkfish and/or penaeid shrimp culture. This was mainly done to address the decline in the production of such major commodities in ponds and/or cages brought about by diseases and mass fish kills caused by intensified culture methods. The present paper focuses on the different salt tolerant Nile tilapia stocks that have been developed and disseminated in the Philippines, the culture practices involved, as well as the prospects for profitable production of Nile tilapia in saline conditions.

Substrate preference for both burying and feeding of sandfish Holothuria scabra juveniles (3–6 g wet body weight) and their associated daily behavior, growth and survival were investigated in laboratory and field experiments using different coastal substrate types (silty mud, sandy mud, and coarse sand) to determine the ideal habitat for potential grow-out culture, sea ranching or stock enhancement of this important sea cucumber species. During the peak hours of burying (03:00–09:00 h) and feeding (15:00–03:00 h), a significantly greater number of sandfish juveniles preferred to bury in (28.3%) and feed on (21.5%) sandy mud, typical of intertidal coastal sand flats. Silty mud was the least preferred substrate for feeding (13.5%) and burying (13.8%). Burying and feeding preferences of sandfish juveniles were not significantly influenced by the presence of seagrass (Thalassia hemprichii) on coarse sand. Growth of sandfish juveniles in the first two weeks of rearing in tanks was significantly greater on coarse sand (growth rate: 0.59 g d⁻¹ or 7.0% d⁻¹), followed by sandy mud (0.34 g d⁻¹ or 4.72% d⁻¹) while OM content of these sediments remain almost unchanged. On silty mud, sandfish juveniles constantly shrunk (−0.02 g d⁻¹ or −0.63% d⁻¹) for 8 weeks while sediment OM content increased. In the field, silty mud substrate of a mangrove pond caused total mortality of sandfish within two weeks, while sandy mud substrate of a sand flat provided significantly higher growth than the control (no sediment), but not significantly different than coarse sand of a seagrass bed. Sandy mud to coarse sand substrates of intertidal sand flats were most preferred by sandfish juveniles while silty mud associated with muddy mangroves and culture ponds seems to be unsuitable that sandfish would opt to avoid. Our results will contribute to the selection of suitable sites for sandfish sea ranching and stock enhancement in coastal areas.

Changes in innate immunity parameters and epinecidin mRNA transcript levels were examined to characterize the non-specific immune response of E. coioides to pathogenic V. harveyi JML1 isolated from affected cage-cultured fish. After fish had been injected with bacteria at a dose causing 30% mortality, blood and tissue samples were collected at 0, 6, 12, 24, 48, 72, 96, 120, and 240 h post-infection (hpi) for assessment of indices such as the oxidative burst (OB) and phagocytic index (PI) of head kidney cells, and lysozyme activity (LYS) and total immunoglobulin (Total Ig) levels of the plasma. The epinecidin mRNA transcript levels (EGE) from skin, gills, liver, kidney, and spleen tissues were also determined by gelbased RT-PCR. Lastly, daily mortality (DM), liver total bacterial load (TBC), and presumptive Vibrio count (TVC) were monitored up to 240 hpi. The results revealed that bacteria proliferated rapidly in fish tissue, reaching peak densities at 24 hpi for both TBC and TVC but was on a downward trend thereafter. The pattern in fish mortality closely correlated with TBC and TVC. Total Ig, OB, and PI in E. coioides were suppressed in the early part of infection when V. harveyi load was high but recovered and later increased as bacterial density declined. LYS and EGE were consistently high and their activities were not hampered by bacterial infection. The study demonstrated that V. harveyi JML1 interacts with E. coioides by transiently inhibiting some immune parameters resulting in mortalities. However, consistently high LYS, upregulated EGE, and resurgent PI, OB and Total Ig conferred resistance and subsequent recovery in the fish. The study provides new insights on the interaction between E. coioides and V. harveyi JML1 that can aid in formulating health management strategies for groupers. Further studies on prophylactic interventions to enhance the innate immune response in grouper during infection with V. harveyi JML1 are suggested.

Male and female Scylla serrata juvenile crabs were stocked separately in cement ponds (14 x 8 x 0.8 m; 90 m3) and reared for 90 days. The study was conducted at the Fisheries Research Station, JAU. Okha, Gujarat. The crabs were fed trash fish and Trochus spp. The survival rates of male and female crabs were higher in Run 1 at 66.11% and 45.55%, respectively, than in Run 2 at 13.9% and 6.1%, respectively. The mean body weights of males (1,704 g) and females (994.5g) in Run 1 were higher compared to those in Run 2 (381.2 g for males and 104.5 g for females). However, there were no significant differences (P>0.05) in the average daily weight gain of 0.19 g day^-1 for males and 0.13 g day-1 for females in Run 1 and 0.16 g day-1 for males and 0.13 g day^-1 for females in Run 2. The water parameter levels were within the optimum ranges for mud crab culture. The results indicate that it is not commercially viable to grow juveniles to market size in cement ponds based on the conditions in this study.

The need for seeds for expansion of the mud crab industry led to the development of the hatchery technology. The nursery technology was developed as this served as a link between the hatchery, which produces megalopae or early crab instars, and the grow-out phase which requires bigger crab juveniles for a higher yield. The nursery has two phases, the first ending with production of crablets with 1- 1.5 cm carapace width (CW) and the second phase with crablets of 2.5-3.0 cm ICW. The more commonly recommended system employs stocking of megalopae or crab instars in net cages installed in ponds. Locally available unprocessed food and commercially available shrimp formulated diet are used for feeding. However, recent studies have successfully used formulated nursery diet for mud crab. One of the main problems in the nursery is cannibalism, and several strategies have been investigated and tried to address the problem.

Mass seed production of mud crab Scylla serrata adopting the best management practices has been done in the hatchery of Rajiv Gandhi Centre for Aquaculture, Thoduvai in Tamil Nadu. Mature female mud crabs from farms and landing centres were procured, screened for White Spot Syndrome Virus and conditioned in the hatchery. The crabs were subjected to unilateral eyestalk ablation whenever necessary and maintained in tanks with sand substrate and aeration. The crabs were fed fresh squid, oyster meat and low value fish. Hatching occurred 9 days after spawning. The newly hatched zoeae were stocked in 5-ton tanks at 80 ind/li. The larvae were fed rotifers and Artemia nauplii. Green water culture system with the use of probiotics was adopted. Enrichment of Artemia was carried out. A hatchery run ranged from 25-30 days. The highest survival rate achieved was 17.5%. This could propel the commercialization of mud crab seed production in India.

Mud crab or mangrove crab (Genus Scylla de Haan) is one of the most extensively cultured and economically important brachyuran crabs from the family Portunidae in Indo-Pacific countries, including India. Mud crabs exhibit variations in colour, size, spination, polygonal pattern and habitat. These contribute to the confusion in their identification. Accurate identification of the species is essential in the breeding programmes of domesticated stocks and is a crucial factor in the success of stock enhancement programmes. The taxonomic uncertainty of the genus Scylla in India is still an issue and several papers are being published using misleading identification. This is the first attempt to resolve the taxonomical ambiguity of mud crabs commonly found in Indian waters using multiple molecular genetic approaches. ITS-1, RAPD, PCRRFLP and mt-DNA sequencing along with traditional morphometric methods were used. Furthermore, a PCR method was developed by which mud crab species in India could be identified rapidly and accurately. The results of gene sequencing along with other molecular markers clearly indicated that the ‘green’ morph of Indian mud crab is S. serrata, while the ‘brown’ one is S. olivacea which was validated using the revised classification of mud crabs by Keenan et al. (1998). The S. serrata commonly mentioned in published literatures from India is S. olivacea and the S. tranquebarica, as believed by many Indian researchers, should be classified as S. serrata. Therefore, caution should be taken while interpreting or implementing the biological, molecular and aquaculture data published in those literatures.

Mud crab is an economically important crustacean commodity in Thailand due to its high nutritional and market value. All the four species of mud crab, Scylla paramamosain, S. olivacea, S. serrata and S. tranquebarica are found in Thailand. The production areas are along the coasts of Gulf of Thailand where S. paramamosain or white mud crab is abundant, and Andaman Sea where S. olivacea or black mud crab is dominant. Data from the Thai Department of Fisheries estimated that the total mud crab production in 2010 was 2,130 mt valued at Baht 322.7 million (US$10.84 million). In the last decade, the production from coastal aquaculture was 6,921 mt valued at Bath 491.4 million (US$16.51 million). The probable cause of the decrease in production is the over exploitation of the wild population. Mud crab culture systems commonly practiced are grow-out (culture from juveniles to market size crabs in ponds), fattening of lean crabs and production of soft-shell crabs. In the past, seedstocks for grow-out culture were collected from the wild. Recently, both wild and hatchery-reared seedstocks are being utilized for farming. Mud crabs for fattening and production of soft-shell rely mainly on wild resources. All culture practices are considered extensive or semiintensive except for soft-shell crab farming which is intensive. The current research and development activities include broodstock and seed production techniques, and formulated feed production. Further technical and financial support are required to improve the survival and production of mud crab. Likewise, support for the transfer of technology to farmers is needed. The lack of seed supply is a major issue facing the mud crab industry in Thailand. A few mud crab hatcheries, which belong to the government, have been established. It is becoming difficult to collect ovigerous females from the wild. Hence, most females are obtained from ponds. Collection of ovigerous females in the wild is prohibited from October to December. Restocking of mud crabs in the natural habitat has become a routine activity to increase the resources.