The morphology of Pseudorhabdosynochus lantauensis is described. It is the most numerous parasite recovered from the gills of cultured orange-spotted grouper Epinephelus coioides in the Philippines and is smaller compared with similar species reported in Hong Kong, Malaysia and Indonesia. This species is characterized by having an overlapping dorsal bar and short copulatory organ. The life cycle of the gill monogenean is also described. One mature parasite lays at least 10-22 eggs/day. Eggs are oval (0.021-0.120 mm) with a spiral filament attached to one end. Eggs hatch into free-swimming larvae (oncomiracidia) within 2-6 d at 30°C and 30 ppt. The rate of hatching of various eggs is highly variable, that is, some eggs hatch in 2 d while others take 6 d. The oncomiracidium can attach to the grouper host within 8 h. Upon attachment, the oncomiracidium metamorphoses to an adult parasite in 4-7 d. The parasite becomes fully mature and delivers eggs in 7 d. Without a host, the life span of oncomiracidium is only 4-8 h. The life cycle is complete in 13-20 days (eggs to oncomiracidium 2-6 d; oncomiracidium to adult parasite 4-7 d; adult to fully mature and egg delivery parasite 7 d). This is the first report on the morphology and life cycle of P. lantauensis from the Philippines.

The aims of this study were to establish an accurate size measurement method and a nutritional condition evaluation method of Holothuria scabra (Jaeger). Although 0.5% KCl and 0.05% MgSO₄ did not induce anaesthesia, 2% menthol–ethanol for 20 min was found to be effective and harmless. The anaesthetization significantly reduced the coefficient of variation of the mean body length and weight by 68% and 43% respectively. During starvation, body size and weight decreased concomitantly, resulting in an unchanged condition factor (body weight/volume), suggesting that the condition factor cannot be used as an index of nutritional condition. Protein, cholesterol and carbohydrate concentrations in the body fluid were analysed to study the relationship with starvation. As the protein and cholesterol concentrations initially increased and then decreased during the starvation period, it is difficult to use them as an index of nutritional condition. The carbohydrate concentration showed a gradual one-fold increase during 10 days of starvation, and it may be used as a proxy for nutritional condition; however, further physiological studies are needed. Body fluid density and volume relative to body size gradually increased and decreased, respectively, during starvation. These methods may be used to correctly monitor the conditions of H. scabra in studies for aquaculture and stock enhancement techniques.

White spot syndrome virus is the most important among the shrimp diseases. It has been devastating the shrimp industry for more than 3 decades. Previous studies reported that greater percentage of yellow colonies on thiosulfate citrate bile salt sucrose agar (yellow vibrios) in the rearing water, abundant supply of natural food such as Chlorella, and the use of the greenwater technology (GW) are some ecological ways of preventing WSSV outbreak. The aim of this study was to investigate the efficiency of the 3 systems against WSSV. Shrimp, experimentally infected with WSSV by feeding with WSSV positive shrimp carcass, was cultured in tanks using three treatments: with tilapia to simulate the GW, seeded with Chlorella, and with molasses added to enhance growth of yellow vibrios. Shrimp cultured in seawater served as the control. Survival was recorded and shrimp were analyzed for WSSV quantification using qPCR upon termination. Analysis showed no significant differences in shrimp survival at 120 h post infection in all treatments and the control. However, from the original viral load of 1.40 × 10¹ WSSV/mg sample, WSSV decreased and was significantly lowest in shrimp cultured using GW (7.0 × 10⁰), compared to the control (4.82 × 10⁵) and the other treatments (3.66 × 10⁵ for molasses added and 4.64 × 10⁵ for Chlorella seeded) in which viral load increased 4–5 times. Shrimp survival was highest in Chlorella seeded treatment and lowest in GW. Nitrogenous waste concentrations were lowest in molasses added water and highest in GW. Results suggest that the GW culture technology provides protection against WSSV while addition of molasses lowers nitrogenous waste concentration. The use of GW in combination with the addition of molasses for shrimp culture is suggested.

Intensification in the grow-out culture of high-value fish requires a large quantity of quality fingerlings. Fingerling production is a component of fish farming that comprises nursery and grow-out culture, and may be a commercial enterprise option for fish farmers with limited pond area. The nursery rearing of the Asian seabass Lates calcarifer (Bloch) was conducted in netcages inside a brackishwater pond. The fish were fed with two isocaloric, high-protein diets formulated at the Southeast Asian Fisheries Development Center (SEAFDEC/AQD) and a control treatment: diets A (40.40% crude protein, CP) and B (46.17% CP), and trashfish (TF) as control. Hatchery-bred seabass early juveniles of two size groups (S₁, 4.0 ± 0.2 g; S₂, 2.40 ± 0.03 g) were stocked at 75–100 fish per m³ and given diets A or B at 6–10% of average body weight (ABW) d^-1, or TF at apparent satiation. Seabass given the formulated diets attained the desired size (≥ 20–40 g) after 45 d but not the fish fed with trashfish. Size and treatments showed significant effects on final ABW, although no significant interaction between these factors was shown to affect body weight. As expected, S₁ fish attained a significantly higher ABW (30.7 ± 18 g) compared with S₂ fish (20.7 ± 11 g) regardless of diet treatment. Seabass fed with trashfish exhibited significantly lower final ABW (6.6 ±1.6 g) than those fed Diet A (33.4 ± 6.5 g) or Diet B (37.1 ± 9.4 g). Fish size did not have any significant effect on specific growth rate (SGR), but diet treatments did. SGR was significantly better when either Diet A (5.2 ± 0.30) or B (5.4 ± 0.20) was used compared with the SGR of seabass fed with trashfish (1.7 ± 0.5). Although size and treatment did not show significant interaction on fish survival, the use of bigger seabass resulted in higher survival (89 ± 11%) compared with smaller seabass (80 ± 11%). Regardless of size, similar survival was attained in seabass fed Diet A (89 ± 6%) or B (95 ± 5%), significantly higher than that in seabass given trashfish (72 ± 6%). An interaction between size at stocking and diet treatment significantly affected protein efficiency ratio (PER). When S₁ fish was used, diets A and B gave similar PER. However, when S₂ fish was used, diet A gave significantly higher PER (2.49 ± 0.02) among the treatments (P < 0.05). Regardless of size, significant differences (P ≤ 0.05) were observed in the mean production cost, revenue and income among the three diet treatments. Moreover, post hoc analysis using Tukey’s HSD test further showed that use of diet B resulted in significantly higher revenue (PhP25,132.80) and income (PhP12,597.47) compared with the two other treatments. Trashfish treatment gave the least revenue (PhP 9,525.60) and negative income (- PhP 1,798.40). Production cost was not significantly different between diets A and B. Hence, diet B is the most economically viable and productive diet treatment. The low break-even price of fingerlings obtained for diet B showed that selling price can still be reduced to lower production cost in grow-out farming.

This study compared co-feeding zooplankton (ZP, mixed copepods and mysids) and formulated diets (FD) supplemented with L-tryptophan (TRP) on the survival and growth of grouper and sea bass fry nursed in brackish water ponds. Grouper (84 fry m⁻³) and sea bass (150 fry m⁻³) were reared for 30 days and 60 days, respectively, in net cages within two separate 743 m² nursery ponds. Five treatments (with three replicates each) were compared (P < 0.05): FD-1 = ZP + basal FD (no added TRP, but containing 0.29% endogenous TRP); FD-2 = ZP + (FD 0.58% TRP); FD-3 = ZP + (FD 1.22% TRP); FD-4 = ZP + (FD 2.50% TRP); and FD-5 = minced fish (Sardinella sp.) + basal FD (no additional TRP). TRP supplementation in grouper diets produced no significant affect on growth but increased survival at rates of 0.58% and above. TRP supplementation at 2.5% (FD-4) produced significantly better sea bass growth than other diets but had no affect on survival. Zooplankton improved both survival and growth in both grouper and sea bass juveniles compared to the minced fish diet, and may be a practical and lower cost alternative to indoor nursing.

White spot sydrome virus (WSSV) is one of the most important viral disease of shrimp. Several studies to control the disease have been done. Tank experiments identified WSSV risk factors related to the physico chemical properties of the water. A few studies reported pond level WSSV risk factors. This study identifies the risk factors associated with essentially two different farming systems: polyculture and semi-intensive monoculture of Penaeus monodon. Data were gathered from a total of 174 shrimp farmers in eight provinces of the Philippines using a structured questionnaire. Forty-seven variables related to pond history and site description, period of culture, pond preparation techniques, water management, culture methods, feed and other inputs, and biosecurity measures were investigated. In the analysis for combined monoculture and polyculture farms, feeding live molluscs was identified as important WSSV risk factors. In addition to feeding live molluscs, sharing of water source with other farms, having the same receiving and water source, larger pond size, and higher stocking density were identified as important WSSV risk factors in monoculture farms. Climate, i.e. stocking during the cold months and sludge removal and its deposition on the dikes were identified as WSSV risk factors in polyculture farms. Protective factors, listed in decreasing significance, were feeding with planktons and high mangrove to pond area ratio, both observed in the dataset with both monoculture and polyculture farms, while only the latter was observed in the dataset for monoculture farms only. No protective factor was observed in the dataset for polyculture farms. This study confirmed the negative effect of sharing water source with other farms and identified several new factors influencing WSSV infection such as feeding live molluscs increases the risk, while feeding with planktons and high mangrove to pond area ratio reduce the risk.

The significant decrease in wild mud crab population highlights the need to manage the resources and domesticate crabs. This paper presents the initial results of the domestication of mud crab Scylla serrata aimed at producing good-quality captive broodstock. The analysis of the genetic structure of the base population was done as a prerequisite for domestication. Adult S. serrata from the northern to southern parts of the Philippines (Cagayan, Camarines, Samar, and Surigao) were obtained for genetic diversity analysis and domestication. Analysis of molecular variance showed that differences in the genetic variability between the four populations were not significant. Moreover, no significant deviation from Hardy–Weinberg Equilibrium was observed in each sample population and even in pooled populations. Body weight was positively correlated with the carapace width. Second spawning occurred 41–46 days after the first spawning and 34 days from second to third spawning. However, there was a decrease in the number of zoea in repeat spawnings. Twenty-four first-generation (F₁) families were produced from the four sites. The duration from spawning of the base population (P₀) to attainment of broodstock size F₁ was 10–14 months. Four second-generation (F₂) families were produced after 11–12 months. Up to the F₂, crabs tested negative for six viruses: white spot syndrome virus, infectious hypodermal and hematopoietic necrosis virus, gill-associated virus, yellow head virus, Taura syndrome virus, and infectious myonecrosis virus. The reproductive performance of P₀ was comparable to the succeeding generations. Several families were obtained from one population in a year. However, due to the cannibalistic behavior of crabs, more space is required for the nursery and grow-out phase. The domestication of S. serrata is the first study done on any mud crab species in the Indo-west Pacific region. The initial results would serve as guide to understand and eliminate the barriers to mud crab domestication. The breeding technology developed from this study will support the production of good-quality seedstock for farming.

Mass mortality of snubnose pompano Trachinotus blochii fry exhibiting dark coloration, anorexia, and abnormal swimming behavior was recently documented at the hatchery of the Aquaculture Department of the Southeast Asian Fisheries Development Center, Philippines. Samples of brain tissues were collected from affected fish and processed for RT-PCR amplification and virus isolation in cell culture. Infected E-11 cells exhibited cytopathic effect characteristic of betanodavirus. Histopathology of moribund fish showed pronounced vacuolations in the brain, spinal cord, and retina. An RT-PCR product of approximately 430 bp was amplified from the culture supernatant of betanodavirus-infected E-11 cells and sequenced. Sequencing of the T4 region of the coat protein gene (RNA 2) revealed clustering of the isolated virus within the red-spotted grouper nervous necrosis virus type. The pathogenicity of the isolated betanodavirus in healthy pompano juveniles and fry was determined via intramuscular injection and immersion challenges, respectively. Higher mortality rates were obtained in challenged fish compared with the controls. An inactivated vaccine was subsequently prepared by treating the clarified betanodavirus with formalin. Pompano juveniles intraperitoneally injected with the inactivated vaccine exhibited neutralizing antibodies from days 15 (mean titer 1:240) to 125 (1:560) with the highest titer noted at day 64 (1:2240) post-vaccination. Additionally, pompano fry bath-vaccinated and consequently bath-challenged with betanodavirus at day 35 post-vaccination showed higher survival rate compared with the control, indicating the potential of the inactivated betanodavirus vaccine against VNN in pompano fry and juveniles.

Viral nervous necrosis (VNN) caused by piscine nodavirus is a devastating disease affecting mainly marine finfish. In the Philippines, VNN was first reported in hatchery-reared grouper (Epinephelus coioides) broodstock in 2001. These broodstock are usually fed with trash fish. It is therefore suspected that contaminated trash fish may be the source of VNN transmission to the broodstock. To confirm the source of contamination, periodic monitoring of the VNN prevalence using RT-PCR was done on different species of trash fish available in the Iloilo Fishing Port Complex and on the wild-caught fish in Panay Gulf. Results showed that most of the trash fish and wild-caught fish were sub-clinically infected or carriers of VNN, and that the virus might have already been established in the environment where they were living. These findings provide strong evidence that trash fish could be the main source of viral contamination in broodstock since they are identified as the only major input in the culture systems. To prevent the transmission of VNN to broodstock through contaminated trash fish, a shift to a broodstock pelleted feed is highly recommended.

Seed production of the seahorse Hippocampus comes was examined using different types of sea water (UV-treated, chlorinated, sand-filtered), and formalin-treated copepod Pseudodiaptomous sp. as a food organism. Growth and survival of newborn seahorses (8.9±0.0 mm stretched height, 0.004 g) were monitored until day 30 after birth. Growth (stretched height and weight) was significantly higher (p<0.05) in UV-treated sea water (41.4±0.5 mm, 0.23±0.00 g) than in chlorinated (33.8±1.4 mm, 0.16±0.00 g) or sand-filtered (32.8±0.1 mm, 0.16±0.00 g) sea water. Survival was significantly higher in UV-treated (65.6±1.1%) and chlorinated (62.2±4.0%) sea water than in sand-filtered sea water (41.1±1.1%). Survival of seahorses fed 30 ppm formalin-treated copepods (95.3±1.8%) was significantly higher (p<0.05) than of seahorses fed untreated copepods (78.7±5.5%) on day 8. On day 15 survival was 78.7±9.68% in seahorses fed formalin-treated copepods and 0% in those fed untreated copepods. By day 30, survival of seahorses fed formalin-treated copepods was 64.7±9.82%. On the day of the final comparison (day 10), there was no difference in size between groups. Thus, the present study demonstrates that survival and growth of newborn seahorses is significantly improved in UV-treated water, and survival is markedly maintained by treating food organisms in formalin.