Eight vertebrate and invertebrate hormones were screened for their effect on population growth, mictic female production, and body size of the marine rotifer Brachionus plicatilis. Growth hormone (GH) or human chorionic gonadotropin (HCG) at 0.0025-25 I.U. ml^-1 and estradio1-17β (E₂), triiodothyronine (T₃), 20-hydroxyecdysone (20-HE), 5-hydroxytryptamine(5-HT), gamma-aminobutyric acid (GABA) or juvenile hormone (JH) at 0.05-50 mg l^-1 were added to 5-ml of Nannochloropsis oculata suspension (7 x 10⁶ cells ml^-1). From an initial density of 1 individual ml^-1, rotifers were cultured with hormones for 48 hours in 22 ppt seawater at 25 °C, in darkness. Rotifers were counted and classified into female types and transferred to a new algal food suspension without hormone every other day until day 8 when body size was measured. Population growth was significantly higher in treatments exposed to GABA (50 mg l^-1), GH (0.0025 and 0.025 I.U. ml^-1), HCG (0.25 and 2.5 I.U. ml^-1), and 5-HT (5 mg l^-1). E₂ caused a decrease in population growth, whereas JH, 20HE, and T₃ had no effect. Mictic female production was significantly higher at 0.05 and 0.5 mg l^-1 JH and 0.05 and 5 mg l^- 5HT. GH (0.0025 and 0.025 I.U. ml^-1), E₂ (50 mg l^-1 ), GABA (0.5, 5 and 50 mg l^-1), and 20-HE (0.05 mg l^-1) treatments had significantly higher mictic female production only on day 8, 6, 4, and 6, respectively. T₃ and hCG had no effect on mictic female production. Lorica length increased by 9.6% and 4.4% in rotifers treated with JH (0.05 mg l^-1) and GABA (5 mg l^-1), respectively. Correspondingly, lorica width increased by 8.9% and 2.6% in these treatments. In comparison, 20-HE-, T₃-, and HCG-treated rotifers were smaller (3.9-8.2%) and GH, 5-HT and E₂ had no effect on rotifer body size.

A protocol for rearing orange-spotted rockcod, Epinephelus suillus in the hatchery is described. The feeding regime consisted of Chlorella, Brachionus, Artemia and minced fish. With this regime, survival rates at Day 24 were 19.8% in 3-ton tanks and only 7.4% in 0.5-ton tanks. From an initial length of 1.62 mm on Day 0, larvae grew to 10.94 mm on Day 24 and 51.4–65.1 mm on Day 60. Larval growth and survival rate were improved when larvae were fed screened (less than 90 μm) Brachionus during the first 2 weeks. Survival was even better among larvae fed Brachionus until Day 35. Artemia, at a density of 3 ml⁻¹, given once daily to larvae in 24 ppt seawater improved growth and survival.

In Japan, vibriosis caused by Vibrio penaeicida usually occurs in cultured kuruma prawn (Penaeus japonicus) during summer and fall. The causative bacterium can easily be detected from overtly diseased prawns, but from apparently healthy prawns the detection rate is low. The results of the conventional isolation method of the pathogen does not seem to reflect the true carrier rate because more prawns often come into overt infection after collection-transport-acclimation procedures, although such data have not been published. In the present study, transport stress was given to apparently healthy prawns to verify the above phenomenon.

Growth performance of juvenile seabass (initial mean body weight, 0.90 ± 0.04 g) fed varying carbohydrate and lipid levels were determined using practical diets in a 2 × 3 factorial experiment. Two carbohydrate levels (15 and 20%) and three lipid levels (6, 12 and 18%) at a fixed protein level of 42.5% were tested. Dietary energy ranged from 284 to 412kcal 100g⁻¹ diet. The fish were reared for 12 weeks in 601 flow-through tanks with aeration in seawater at 32%. and at 26.5–29 °C. Higher weight gains were observed in fish fed diets containing 20% carbohydrate with 12 or 18% lipid. Lowest specific growth rate was observed in fish fed the 15% carbohydrate at 6% lipid. Survival was 100% in all treatments. The feed conversion ratios for fish fed 20% carbohydrate at 12 or 18% lipid, and 15% carbohydrate with 12% lipid were best. Specific growth rate and weight gain did not differ at lower dietary lipid (12-6% or 18-12%) despite an increase of dietary carbohydrate indicating a sparing of lipid by carbohydrate as an energy source. Dietary lipid at 18% (1:1 ratio of cod liver oil and soybean oil) seems to be excessive for seabass. Based on this study, we recommend a carbohydrate level of 20% in diets containing lipid levels ranging from 6 to 18%.

This paper reviews the history and status of the milkfish fry fishery and hatchery and examines the issue of fry shortage in some detail. The fry fishery in the Philippines is a well developed industry that uses efficient indigenous technology, employs a quarter-million people, and provides income to local governments through fry ground concessions or fry gathering permits. The fry fishery is determined by where and when milkfish spawn. Fry perishability and the lack of an accurate accounting method shape industry practices and make it difficult to quantify the fry supply. Catch data are lacking, but the milkfish production of 100,000-240,000 mt indicate that fry catches ranged 0.8-2 billion a year during the past 25 years, and averaged at least a billion a year during the last five years. Milkfish farming has intensified in brackishwater ponds (especially in former shrimp farms) and has expanded into freshwater and marine pens and cages. However, there are no data on the farm areas currently under operation under different stocking rates, and fry requirements can only be roughly estimated for a given set of assumptions. If the Philippines double its current total milkfish production to 300,000 mt to support a larger population, then hatcheries would have to provide about one billion fry, in increments of perhaps 100 million a year, over the next decay. About 1000 females and 1000 males are required 100 million fry. Milkfish broodstock and hatchery technologies suitable for the Philippines have long been developed by the SEAFDEC Aquaculture Department, but only recently caught the attention of Filipino hatchery operators and milkfish farmers. On the other hand, milkfish farming is market-driven and profit- motivated and intensification can not prosper when production cost is high and farm-gate price is low. Under these conditions, the fry shortage is not immediate and the private sector has time to establish milkfish broodstocks and hatcheries. Refinement are needed in a fry fishery, hatcheries, grow-out operations, post-harvest processing and marketing – to assure increased production and the sustainability of the milkfish industry.

One day old red-spotted grouper (Epinephelus coioides) larvae from SEAFDEC, Iloilo, were packed at 3.300 ind/L and transported to Dagupan, Pangasinan for larval rearing. Transport time was about 10 hours. More than 90% of the larvae were active after transport. These were reared in two 7-on tanks (Tanks 1 and 2) using Acartia nauplii and rotifers as a initial food and in one 10-ton tank (Tank 3) provided with rotifers only. Feeding incidence at the onset of feeding (Day 3) was higher (90-95%) in Tanks 1 and 2 than in tank 3 (85%). All larvae sampled from days 4 – 10 in Tanks 1 and 2 had food in the gut while feeding incidence in Tank 3 was variable (75-100%). Larvae in Tanks 1 and 2 showed consistently higher food electivity for Acartia nauplii than rotifers. Higher survival rates were observed in Day 13 in tanks provided with copepod nauplii (16-18%) than with the rotifers only (2%). Average total length on Day 13 was higher in copepod-fed larvae (4.5 ± 0.5 mm) than larvae fed with rotifers only (3.0 ± 0.3mm). All larvae fed with rotifers alone died on Day 15. A total of 675 larvae were harvested on Day 45 from Tanks 1 and 2. These results indicate the feasibility of transporting one day old E. coioides larvae for at least 10 h and of using copepod nauplii as food for the first feeding E. coioides larvae.

Three species of agarophytes (Gracilaria changii, G. manilaensis and Gracilariopsis bailinae) collected along the mud flats of Iloilo were investigated to determine the monthly variation in agar yield (%), gel strength (g cm^-2), gelling and melting temperatures (°C) and sulfate content (µg mg^-1). Results show that Gracilariopsis bailinae collected at Zarraga gave a higher gel strength (784 g cm^-2) than that collected at Estancia (637 g cm^-2), however, the latter gave a higher agar yield (22%). A year-round source of agar was demonstrated in G. bailinae in both places while Gracilaria changii (January to June) and G. manilaensis (April to June) were seasonal. Higher agar yield and gel strength were measured from G. changii than in G. manilaensis. Gracilariopsis bailinae showed agar qualities superior to those of the two other species, hence it is a good species to harvest and develop for mariculture and consequently for agar manufacture.

Diets low in animal but high in plant protein were enhanced with a chemoattractant FinnStim (FS), a betaine/amino additive. These were fed to juvenile shrimp, Penaeus monodon, in three tank experiments. All diets were formulated to be isonitrogenous (35% protein) and isocaloric. In run 1, where soybean meal was used as the plant protein source (33%), graded levels of FS (0 to 2.0%) were added to the basic mix (B). Shrimp fed the diet with 1% FS had a significantly ( alpha =0.05) higher weight gain than the other treatments and a feed conversion ratio (FCR) which was higher than B and B+2% FS but not significantly different from the other FS levels. However, survival, specific growth rate (SGR) and feed intake were similar. In run 2 diet palatability, which may be affected by plant protein, was considered. Diets with a lower soybean meal content (18%) and 16% papaya leaf meal, with and without 1% FS, were tested. A higher weight gain and SGR were obtained for shrimp fed FS but survival, feed intake and FCR were not significantly different from those without FS. In run 3, where leaf meal was increased to 25%, shrimp fed 1% FS yielded a significantly better weight gain, SGR, feed intake and FCR, but survival rates were not significantly different. FS did not increase feed intake but may have caused faster feed consumption, resulting in less feed disintegration and nutrient loss. It could also have acted as a stimulant and counteracted the palatability problem of the 25% leaf meal diet. However, much of the response was evidently caused by the physiological role of betaine as methyl donor and osmoprotectant.

Zooplankton collected by the torch lighting method were investigated in a tropical coastal seawater pond in eastern Thailand. Copepods of the genus Acartia, such as A. sinjiensis, A. erythaea and A. pacifica, were predominant among the zooplankton collected. A. sinjiensis occurred almost throughout the year with a prolonged peak season from August to April. The highest abundance of adult A. sinjiensis aggregated under the light reached 35,700 individuals•l^-1. The occurrence of A. erythaea and A. pacifica was intermittent with a short-term peak from March to April, during which their abundance was higher than A. sinjeinsis. The combination of water temperature and salinity was suggested to affect or regulate the biomass of these Acartia species. Among the Acartia species, A. sinjiensis seems to be the most important as a food organism available for marine fish larval rearing in eastern Thailand.

An 8-week feeding trial was conducted to determine the dietary requirement of postlarval Penaeus monodon for the sulfur-containing amino acid methionine. Shrimp postlarvae (mean weight 21 ± 0.3 mg) were reared in 40-1 fiberglass tanks in a flow-through seawater system. Test diets (37% protein and 360 kcal per 100 g diet) were formulated containing casein-gelatin as protein sources and supplemented with crystalline amino acids to simulate the amino acid pattern in shrimp tissue protein except methionine. The diets contained graded levels of methionine at a range of 0.72–1.12% of the diet or 2.0–3.0% of protein. In diet preparation, the crystalline amino acids were pre-coated with carboxymethylcellulose (CMC) to reduce leaching. Diets were further coated with CMC, cornstarch, and κ-carrageenan to improve water stability and the diet pH was kept at 7.0–7.2 by neutralization with 6N NaOH. Shrimp were fed the diets at 25–30% of their biomass thrice daily. At termination of the feeding experiment, various parameters including growth, survival, and feed conversion efficiency were determined and nutritional deficiency signs noted. The methionine requirement was determined from the relationship between weight gain and dietary methionine level using the broken-line regression method. The requirement of P. monodon postlarvae for methionine was 0.89% of the diet or 2.4% of protein. In a diet containing 0.41% cystine, the total sulfur amino acid requirement (methionine + cystine) would be 1.3% of the diet or 3.5% of protein. This requirement is slightly lower than the methionine level present in shrimp tissue protein.