A didymozoid trematode encapsulated in the gills of orange-spotted grouper, Epinephelus coioides Hamilton, was observed in October 1997 and September 1999 among pond-reared fish in the Philippines. Capsule prevalence was 33% and 18% and mean intensity 2 and 1, respectively. The opaque-white and yellowish capsules were found only on the first gill arch and were attached lengthwise along the posterior surface of the primary gill filaments. When the capsules were opened, long thread-like worms were revealed, which were identified as Gonapodasmius epinepheli Abdul-Salam, Sreelatha and Farah. The parasites were encapsulated between the basement membrane of the epithelium and the efferent artery of the gill filament. The response of the host included mild hyperplasia of the interlamellar epithelium and an increase in the number of mucous cells.

The approximate levels of dietary protein and energy that would sustain good growth and survival of the mangrove red snapper Lutjanus argentimaculatus (Forsskal) were determined in two feeding experiments. In the preliminary experiment, six fish meal-based diets were formulated to contain three protein levels (35%, 42.5% and 50%) and two lipid levels (6% and 12%) for each protein, with dietary energy ranging from 14.6 MJ kg⁻¹ to 20.5 MJ kg⁻¹. The protein to energy (P/E) ratios of diets ranged from 20.6 mg protein kJ⁻¹ to 27.5 mg protein kJ⁻¹. Diets were fed for 100 days to triplicate groups of snappers with an average initial weight of 24.8 ± 0.4 g. No significant interaction between different levels of protein and lipid was observed. Survival rates (93.8% to 100%), feed conversion ratios (FCR) (2.61–3.06) and condition factors (K) were not affected by different dietary treatments. Regardless of lipid level, fish fed 50% protein diets had a significantly higher specific growth rate (SGR) than fish fed the 35% protein diets, but not compared with the 42.5% diets (P < 0.05). Increasing lipid to 12% in all protein levels resulted in no improvement in growth over the 6% level. Fish body moisture did not vary while lipid levels based on dry matter were high (27.9% to 33.7%). Snapper appear to require more than 40% dietary protein and a high dietary energy level for good growth. In the second experiment, fish (21.1 ± 0.1 g) in four replicate groups were fed for 94 days with three diets (39%, 44% and 49% protein with P/E ratios of 21.1, 23.3 and 25.5 mg protein kJ⁻¹ respectively) containing similar dietary energy levels of about 19 MJ kg⁻¹. Average final weight, SGR and FCR were significantly higher in diets containing 44% and 49% protein diets (P > 0.05). There were no differences in survival rates, protein efficiency ratio (PER) and nutrient composition of snapper flesh. All fish had fatty livers. Results indicated that the diet containing 44% protein with a P/E ratio of 23.3 mg protein kJ⁻¹ was optimum for snapper growth under the experimental conditions used in the study.

The performance of wild Epinephelus coioides juveniles was compared by feeding with live tilapia juveniles, fish by-catch, and formulated diet for 5 months in grow-out ponds. To minimize cannibalism, the groupers were graded into small (BW=24.9±7.3 g), medium (45.8±5.7 g), and large (84.1±30.0 g) size groups as block in a Randomized Complete Block Design (RCBD) and reared in nine 350-m² ponds. To supply the tilapia juveniles, adult tilapia were grown 2 months prior to stocking of grouper at a rate of 15 tilapia/grouper. Grouper fed by-catch were significantly higher (P<0.01) than the other treatments in terms of final length and total production. The quality of by-catch could be gleaned by its efficient feed conversion ratio (FCR) of 1.0 (dry basis), significantly better (P<0.01) than the formulated diet that had an FCR of 2.8. Using by-catch, 47% of the harvest weighed >400 g and only 14% was classified <200 g. The cost of juvenile grouper and feeds represented 88–89% of the total investment in all treatments. Economic sensitivity analysis showed that a combination of improvement in factors such as price of grouper juveniles, feeds, yield, survival, and FCR would result in higher return-on-investment (ROI). When cost and returns were considered, feeding juveniles with by-catch was more profitable because it resulted in net income of Php 361,623/ha/year, an ROI of 155%, and a payback period of 0.4 year. The results clearly show that these economic indicators appear to be attractive, thus making grouper pond culture using by-catch a viable industry. More research efforts should, however, be directed towards developing a cost-effective formulated diet for the grow-out culture of E. coioides.

This study examined the influence of different carotenoids on growth and some immune indices in rainbow trout. Six semipurified casein-based diets were formulated to contain one of three different carotenoids: astaxanthin, canthaxanthin and β-carotene, at 100 mg kg⁻¹, each of them with vitamins A, C and E either added or omitted. The two control diets contained no carotenoids and were either with or without the vitamins. Rainbow trout weighing about 140 g were fed the diets for 9 weeks. Specific growth rate, feed:gain ratio and nonspecific immune parameters were determined. Growth and feed conversion were similar among the groups. Immune parameters like production of reactive oxygen species by head kidney leukocytes and plasma total immunoglobulin levels did not vary with the treatment. Serum complement activity in both β-carotene groups and the vitamin-containing astaxanthin group were significantly higher than both the control fish. Serum lysozyme activity in the vitamin-containing β-carotene and astaxanthin groups were significantly different from both control groups. Phagocytic activity was also high in the vitamin-containing β-carotene and astaxanthin groups compared with the controls. For phagocytic index, in addition to the foregoing groups, the vitamin-containing canthaxanthin group gave better results compared with the controls. The vitamin-containing astaxanthin and β-carotene groups also exhibited better nonspecific cytotoxicity for the peripheral blood lymphocytes at all effector-to-target ratios. Thus, among the carotenoids studied, β-carotene and astaxanthin elevated humoral factors such as serum complement and lysozyme activity, as well as cellular factors such as phagocytosis and nonspecific cytotoxicity. In the presence of the vitamins the carotenoids exerted a greater influence on the bio-defense mechanisms of rainbow trout.

Twenty-month-old bighead carp, Aristichthys nobilis (Richardson), were fed prepared dry diets for 20 months in cages in Laguna de Bay, Philippines, to determine the effect on reproductive performance. The experimental diets were similar in composition except for the combinations of vitamins being tested. Diet 1 was supplemented with vitamins A, E and C; diets 2, 3 and 4 each lacked one of the supplementary vitamins; and diet 5 did not include any vitamin supplementation. Bighead carp that relied solely on natural food without a prepared diet served as a control. The total of six treatments each had two replicates. Results showed that the onset of gonad maturation was 2–3 months earlier in the fish that were fed the prepared diets regardless of vitamin supplementation, when compared with the fish that were fed natural food (control). Moreover, the prepared diets enhanced egg hatchability which was significantly higher in fish that were fed diet 1 (+ vitamins A, E and C, 80.5 ± 18.1%) and diet 3 (– vitamin E, 78.5 ± 1.1%) than in those fish that were fed natural food (control) (36.5 ± 31.3%). Mean number of 3-day-old larvae was highest in fish fed on diet 1 (34 525 ± 1732), followed closely by fish that were fed diet 3 (32 420 ± 3909). A low number of 3-day-old larvae was obtained from fish fed the natural diet (14 490 ± 4331) as well as in fish that were fed diet 2 (– vitamin A, 14 347 ± 4863), diet 4 (– vitamin C, 21 407 ± 5840) and diet 5 (– vitamin A, E and C, 12 191 ± 1439). Other criteria for reproduction such as relative fecundity, fertilization rate, and hatching rate did not differ significantly (P > 0.05) among treatments. The addition of vitamins also had no significant effects on weight gain of adult fish.

A total of 24 morphological abnormalities associated with the Runt-Deformity Syndrome (RDS) is reported for the first time in 17- to 18-mo old F₃ generation Penaeus monodon (>40 mm CL) belonging to three breeding families. Although diagnosed as positive for the infectious hypodermal and hematopoietic necrosis virus (IHHNV), the shrimp appeared normal at 9 to 10 mo when they were procured from a commercial facility in Antique, central Philippines, in September 1996. The abnormalities affected either specific shrimp organs and appendages (e.g., rostrum, antennae, uropods) or the whole body (e.g., shell color and hardness). A two-way analysis of variance was used to evaluate differences in the morphometric characters rostral length (RL), carapace length (CL), abdominal length (AL), body length (BL), total length (TL), carapace width (CW), 1^st abdominal segment width (AS₁W), and body weight (BW) and the morphometric ratios RL:CL, CL:AL, and CW:AS₁W by sex and stock (3 families and wild controls). Female P. monodon had significantly larger CL, AL, BL, TL, CW, and BW than males, regardless of stock. Wild females had longer BL and TL than cultured ones, whereas wild male shrimp had shorter CL, CW, and BW than cultured male P. monodon. Cultured shrimp had significantly higher CL:AL and CW:AS₁W ratios and lower RL:CL ratio compared to wild P. monodon. The shorter and narrower abdomen relative to the carapace gave the shrimp a “runted” or dwarf appearance characteristic of RDS earlier described in Litopenaeus vannamei with IHHNV. Confirmed by parallel studies, IHHNV infection of the cultured P. monodon may account for their cuticular deformities, slower growth, and smaller sizes. The appearance of deformities in older (and bigger) P. monodon suggests that RDS expression is dependent on age and size. Examination for external abnormalities and evaluation of the three morphometric ratios may complement existing screening protocols for diseases and growth rates in shrimp breeding programs. Cultured giant tiger prawn also had lower sperm count, greater proportion of dead and abnormal sperm, and lower incidence of mating (absence of sperm in thelyca) compared to wild P. monodon.

Most mangrove reforestation program in the Philippines and elsewhere in Asia focus on the genus Rhizophora, hence there is a need to identify and develop planting and harvesting techniques for other mangrove species, especially those in high demand by coastal communities. The yellow mangrove Ceriops tagal is one such species. Its many uses as firewood, poles for fish-corrals and traps, house construction, medicine (wound cleansing, treatment of hemmorhages), in the production of dyes (for dyeing fish nets, ropes, cloth and rice as a festive food) and as a mordant from bark are widely reported from the Philippines and all over Southeast and South Asia. An extensive sea-based industry for collecting C. tagal bark or tungog existed in the Philippines in the 1930s-1950s. It is heretofore described as undocumented industry including the boats used, collecting sites, markets, financing system and profit-sharing. Because C. tagal lacks reserve meristems, cutting of the trunk during bark gathering causes tree mortality. This explains the wholesale disappearance of the species from areas where it has been harvested throughout the Philippines, Southeast and South Asia, and East Africa. Research is needed to refine planting techniques and develop bark harvesting methods that do not kill the tree. Until nondestructive procedures for bark collection are finally perfected, C. tagal stands can be planted and harvested on a rotation basis.

The egg morphometry and lipid and protein components were determined in induced spawns (n = 14) of the sea bass, Lates calcarifer, to identify measures of egg quality. Based on fertilization and hatching rates, the spawns were classified either in Group I, (zero fertilization) or Group II (where fertilization and hatching occurred). The egg morphometry did not differ between the two groups (p > 0.05). The total lipid was higher in Group II than in Group I, although the difference was not significant (p > 0.05). The EPA and linoleic acid were significantly higher in Group II (p < 0.05). There were positive correlations between the total saturated fatty acids and fertilization rate (p < 0.05; r = 0.58), the total saturated fatty acids and percentage of normal zygotes (p < 0.02; r = 0.62), and DHA and the percentage of normal zygotes (p < 0.04; r = 0.56). The total protein and FAAs were higher in Group I than in Group II, but the differences were not significant (p > 0.05). Proline, glycine, p-ethanolamine, and aspartic acid were significantly higher in Group II (p < 0.05), while tyrosine and glutamic acid were significantly higher in Group I (p < 0.05). Phosphoserine and fertilization rate were positively correlated (p < 0.03; r = 0.60), as well as aspartic acid and hatching rate (p < 0.05; r = 0.54). Arginine was negatively correlated with fertilization rate (p < 0.03; r = -0.61) and the percentage of normal zygotes (p < 0.03; r = -0.63). Serine was inversely correlated with yolk volume of the newly-hatched larvae (p < 0.03; r = -0.77). The moisture content of the eggs, which was significantly higher in Group II than in Group I (p < 0.03), was directly correlated with the FAAs:protein ratio (p < 0.03; r = 0.76). The present results reveal egg components that may be used as quality measures in induced spawns of sea bass, a euryhaline teleost that spawn pelagic eggs containing an oil globule.

The reproductive performance of female mud crabs was evaluated as affected by various diets. Dietary treatments were as follows: D₁ — natural diet (mussel meat, squid, trash fish); D₂ — combination of natural and formulated diets; D₃ — formulated diet. Pond-sourced broodstock, with initial body weight of 300–400 g, were tagged in their carapace then stocked in three units of 10 m³ broodstock tanks at eight females per tank. Half of the females were ablated and the other half were intact. Spawnings were monitored and berried females were transferred to individual 500-l tanks for incubation of eggs. Four experimental runs were conducted. Broodstock response in terms of number of spawnings, spawnings with hatching, fecundity, egg fertilization rate, total zoea produced and broodstock survival was enhanced in females fed the mixed diet (D₂) compared to those fed the natural diet (D₁) or the formulated diet (D₃). Larval quality measured as larval stage index followed the same trend. Results further showed that intact females fed diets D₁ and D₂ gave higher numerical values in reproductive performance and zoea growth index than ablated females while ablated females fed diet D₃ performed better than their intact counterparts. This may be attributed to presence of essential nutrients and vitamins A, C, E in the formulated diet. Latent period from gonadal maturation to first spawning was shortened by eyestalk ablation. Use of a combined diet would ensure the production of good quality eggs and large numbers of zoea with the best chance of completing the larval stages and thus, would serve as an appropriate starting point in establishing a viable mud crab aquaculture.

Halophytophthora species are commonly isolated from fallen mangrove leaves from early to late stages of decay. In this study we show that these organisms are well adpted to mangrove habitats as they have a wide tolerance to varying levels of pH, salinity and temperature. They also produce, abundant zoospores, and are chemotactically attracted to decaying mangrove leaves, and can readily attach to suitable substrata. In general, the four tested isolates (H. vesicula, H. avicennae, H. kandeliae and H. bahamensis) grew at pH 6-9, with maximum growth recorded at neutral pH. Vegetative growth and sporulation were observed over a wide range of salinities (from freshwater to marine) and temperatures, although optimum requirements varied from species to species. Zoospores of Halophytophthora spp. were chemotactically attracted to mangrove leaf-extracts and some other compounds that are common to the surrounding environment. The zoospores attached and germinated on both artificial (glass coverslips and polycarbonate membranes) and natural (mangrove leaves) substrata. Scanning electron micrographs show that newly attached zoospores, cysts, and germinating cystospores of H. vesicula produced fibrillar adhesive mucilage for attachement as was evident by debris sticking to their tips. More adhesive mucilage was produced by encysted and germinating cystospores on natural as compared to artificial substrata. Cystospores and germlings of H. vesicula and H. avicennae were also found to attach firmly to a perspex disc even after being subjected to a high shear stress of 3.19 Newton per square meter (Nm^-2). Enzyme treatment and staining of attached cystospores indicate that the adhesive produced is composed of acidic polysaccharide with α-1, 4 linkages, and with either sulphate or phosphate functional groups. Once the cystospores were attached to the substratum, they could not be readily dislodged, and successful germination and colonization followed.