Southeast Asian Fisheries Development Center
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AQD Matters 2025 November – December
No full textIn this issue: 1) SEAFDEC/AQD supports pilot oyster culture initiative in Estancia, Iloilo; 2) SEAFDEC/AQD presents updates at 32nd PTAC meeting; 3) SEAFDEC/AQD boosts rural freshwater aquaculture through training; 4) SEAFDEC/AQD research head presents Philippine fish disease issues; 5) 1.67 tons of pompano harvested; 6) SEAFDEC/AQD joins aquaculture dialogue at PEF forum; 7) Okinawa researcher welcomed for seaweed aquaculture exchange; 8) 2025 Christmas Party Celebration; 9) 25 years of SEAFDEC FishWorld: Connecting aquaculture science and society; 10) Former SEAFDEC/AQD staff presents study results on Atlantic cod vaccine; 11) FishWorld hold Sci-Art contests to promote aquatic sustainability; 12) SEAFDEC/AQD staff completes specialized training in Japa
Mangrove crab culture
Full text linkThis brochure provides a comprehensive guide on the culture and farming of mangrove crabs (Scylla spp.), highlighting key aspects of hatchery, nursery, and grow-out operations. It covers species identification, broodstock selection, larval rearing techniques, and essential water quality parameters for successful crab farming. Detailed information on nursery site selection, stocking densities, feeding strategies, and transportation methods for crablets is also included.
Additionally, the brochure presents an economic analysis of mangrove crab farming, outlining the costs, returns, and profitability based on monitored market prices. With proper management practices, mangrove crab aquaculture offers a sustainable and profitable venture for farmers and entrepreneurs in the industry
AQD Matters 2025 January - February
No full textIn this issue: 1) Bangsamoro eyes lapu-lapu farming with SEAFDEC expertise; 2) Equipment delivered for BFAR-SEAFDEC Feed Mill in Tigbauan; 3) Aquaculture training draws 296 trainees in 2024; 4) SEAFDEC/AQD employees attend "Pag-IBIGfluencer" seminar; 5) Temasek University sends experts to SEAFDEC/AQD for training; 6) SEAFDEC/AQD conducts training on oyster seed production; 7) 7 complete training course on tilapia hatchery and grow-out operations; 8) More seaweed samples collected to boost research; 9) DFA officials visit SEAFDEC/AQD stations; 10) Memorandum inked for SEAFDEC-LGU collaboration for sea cucumber project; 11) Pest to Feed: Snail as supplemental diet for pompano
Hatchery production of sea cucumbers: Status, problems and directions
No full textSea cucumbers are ecologically and economically important marine invertebrates, whose wild populations have been threatened by overfishing in recent decades. The rapid decline in wild stocks was driven by high market prices of sea cucumber products for food and medicine. Fortunately, recent developments in hatchery seed production technologies have paved the way towards establishing a more sustainable sea cucumber industry through aquaculture without dependence on massive collections from natural populations
Dietary crude ulvan from Ulva intestinalis enhances growth, salinity stress tolerance, and immunity against Vibrio harveyi in early juvenile milkfish Chanos chanos
No full textUlva green seaweeds are known for their rapid growth and limited commercial value, and hold significant potential as sources of bioactive compounds for aquaculture. Among these, the sulfated polysaccharide ulvan has shown promising growth-promoting and immunostimulatory properties. These properties may offer a natural solution to vibriosis caused by Vibrio harveyi that hinders the sustainability of milkfish (Chanos chanos) nursery production. To evaluate this potential, a 30-day feeding trial was conducted in a completely randomized design. Five dietary treatments in triplicate, including a control diet without ulvan and four diets supplemented with graded levels of ulvan (10, 50, 100, and 500 mg kg−1) were evaluated on early juvenile C. chanos (14.62 mg mean weight). Diets with 10 and 50 mg kg−1 ulvan significantly increased weight gain, specific growth rate, and protein efficiency ratio, while lowering the feed conversion ratio compared to the control group and higher ulvan doses (100 and 500 mg kg−1). Fish fed as little as 10 mg kg−1 ulvan also demonstrated enhanced salinity stress tolerance as evidenced by their higher cumulative stress index values. Further analysis of immune gene expression revealed that supplementation of 10 mg kg−1 ulvan significantly improved immune response by upregulating TLR5, IL6, and LEAP2 mRNA expression levels, resulting in higher survival rates following a V. harveyi bacterial challenge. Overall, these results indicate that adding 10 mg kg−1 ulvan to the nursery C. chanos diet is practical and efficient to boost growth and immunity, offering a promising solution to enhance nursery resilience to V. harveyi
Comparison of gonad development between wild and hatchery-bred silver therapon Leiopotherapon plumbeus (Teleostei: Teraponidae) during an annual reproductive cycle
No full textThis study compared gonad development between wild-sourced and hatchery-bred silver therapon Leiopotherapon plumbeus. Wild fish from the east bay area of Laguna de Bay, Philippines, and hatchery-bred stocks grown to adult size in outdoor tanks were sampled, and somatic condition, gonad histology, gonadosomatic index (GSI), gut index (GI), and hepatosomatic index (HSI) were assessed during the annual reproductive cycle. Hatchery-bred fish condition was generally better than that of wild-sourced fish as a consequence of readily available food resources and environmental conditions. Hatchery-bred male GSIs were significantly higher than in wild male fish in November to February, coinciding with low water temperatures. However, female GSIs were significantly higher in July and November to December for the hatchery-bred fish, and in January to April for the wild-sourced fish. Together with spermatozoa and primary growth oocytes which were most abundant in the gonads, the presence of other gametogenic stages supports asynchronous gonad development. Hatchery-reared fish showed significantly higher GIs during the spawning season over their wild counterparts. Generally, mean HSI, regardless of sex, was also higher among hatchery-bred fish. These results suggest marked differences in the somatic and reproductive potential of wild and hatchery-bred silver therapon, although the presence of spermatozoa and vitellogenic oocytes in the gonads may allow this species to reproduce year-round.Funding for this study was provided by SEAFDEC Aquaculture Department (Study Code: Br-02-F2015B)
Effects of restricted feeding rates on growth, production, and economics of Nile tilapia (Oreochromis niloticus) and giant freshwater prawn (Macrobrachium rosenbergii) polyculture in pond-based biofloc and traditional grow-out system
No full textThe combined effects of restricted feeding rates [50–75% apparent satiation (AS) and 100% AS] and culture systems [biofloc (BFT) and traditional pond system (TP)] on the growth, production, and economics of Nile tilapia-freshwater prawn polyculture were examined in a 2 × 2 factorial feeding trial for 120 days. Each treatment was carried out in triplicate following complete randomized design. Nile tilapia fingerlings (2.09 g) and freshwater prawn post larvae (PL20; 0.05 g) were stocked at an initial density ratio of 6:6 individuals/m2. Lower dissolved oxygen (DO) and higher Total Ammonia Nitrogen (TAN) and nitrite concentrations were observed in BFT system. Similarly, higher levels of DO were recorded in 50–75% AS-fed group, while TAN, nitrite, nitrate, and total suspended solids (TSS) were significantly higher at 100% AS-fed group. Culture system, feeding rate, and their interactions had significant effect on final body weight (FBW) and daily growth rate (DGR) of Nile tilapia. Lower FCR in Nile tilapia was noted in both BFT system and 50–75% AS-fed group. For freshwater prawn, the highest FBW and DGR were obtained in BFT system and fed 100% AS. However, survival rates and condition factor did not differ across all treatments for both species. Higher yield for both species and more large-size tilapia were obtained when fed at 100% AS. An increase in yield and significant improvement on the size distribution of prawns were also achieved in BFT system. Although both BFT and 100% AS have led to better performance, cost and return analysis have instead revealed better profitability using TP system and feeding rate of 50–75% AS. The lower cost of production in these treatments has economically compensated for the unfavorable growth, yield, and size distribution.The authors thank SEAFDEC Aquaculture Department for funding this study under the code TV-04-F2021T
Single initial inoculation of bioflocs maintains water quality in the long-term culture collection of Brachionus plicatilis
No full textWhile rotifers are important first live feed in marine fish hatcheries, maintaining the rotifer culture collection by feeding live microalgae and water exchange is laborious and costly. It is therefore necessary to streamline the culture collection protocol and reduce operating costs. The use of microalgal paste in rotifer production is well documented, but there is limited information on its use in rotifer culture collection because of its ability to deteriorate water quality, such as increasing unionized ammonia (NH3). This study aimed to determine the effectiveness of bioflocs (BF) in regulating NH3 in rotifer culture collection fed microalgal paste Fresh Chlorella V12 (CV12) under zero-water exchange (ZWE) conditions for 42 days. The marine rotifers Brachionus plicatilis were subjected to six treatments, namely: (1) Nannochloropsis oculata (Nanno) × weekly water exchange (WWE), Nanno × WWE as the control, (2) CV12 × WWE, (3) Nanno × ZWE, (4) CV12 × ZWE, (5) Nanno + BF × ZWE, and (6) CV12 + BF × ZWE. Rotifer density was estimated every 3 days, while NH3 was measured weekly. Bacterial compositions were determined. On day 42, the lowest NH3 was observed in CV12 + BF × ZWE, which was significantly different from CV12 × WWE and CV12 × ZWE. Rotifer density was higher in Nanno + BF × ZWE and CV12 + BF × ZWE than in CV12 × ZWE, but egg-bearing rotifers were similar in all treatments on day 42. Single initial inoculation of BF maintains water quality by regulating NH3 concentration via the activity of ammonia oxidizer Nitrosomonas nitrosa and the bacterial groups under phylum Chloroflexota in the long-term B. plicatilis culture collection and that microalgal paste combined with BF can be a cost-effective alternative to live microalgae.This research was supported by the Program on Open Innovation Platforms for Industry-academia Co-creation (COI-NEXT), Japan Science Technology Agency (JPMJPF2117, 2021), and Interdisciplinary Collaborative Research, AORI, the University of Tokyo (General Collaborative Research #1, 2022)
Stocking density effects on growth performance of glass eels (Anguilla bicolor pacifica) in outdoor tank conditions
No full textOptimizing stocking density is necessary to maximize the production efficiency of farmed fish. This study examined the effect of stocking density on the growth performance of the Pacific shortfin eel Anguilla bicolor pacifica reared in outdoor tank conditions. Glass eels (0.72 ± 0.03 g mean body weight [BW]) were stocked at 50 and 100 individuals m−2 in 6 4-m2 outdoor tanks with a flow-through system set up in triplicate. Eels were individually measured for total length and BW, followed by blood sampling at the end of the 286-d trial. Glass eels stocked at a density of 50 m−2 exhibited significantly higher specific growth rate, feed efficiency, and protein efficiency ratio. However, survival, final BW, percent weight gain, biomass, biometric indices, and Fulton’s condition factor were not significantly different between density groups. Although size class distribution was not significantly affected by stocking density, a higher proportion of larger eels (> 50 g) was evident at low stocking density. The coefficients of variation in both length and weight and in skewness were likewise slightly reduced at low stocking density. In contrast, high stocking density resulted in significantly elevated levels of serum total protein. Partial costs-and-returns analysis showed that 50 m−2 density resulted in higher net profit and profit index. These results suggest that under outdoor tank conditions, a stocking density of 50 m−2 will result in higher growth rate and feed utilization, less size variation, better physiological condition, and higher net returns for the culture of A. bicolor pacifica.Funding for this study was provided by the Japan-ASEAN Integration Fund (Study code: Br-02-Y2018B) and the Government of Japan Trust Fund (Study codes: 8300-B-RD-FD0415 and 8300-B-RD-FD0120)