This paper attempts to present recent developments and techniques in breeding, seed production, genetics, feed development, and fish health management. Most of the innovative findings come from work done on well-studied species such as salmonids and carps while investigations done on tropical species are cited.

Two separate experiments on transmission of epizootic ulcerative syndrome (EUS) to naive snakehead (Ophicephalus striatus) by cohabitation with EUS-positive snakehead in EUS-enzootic environment and exposure to EUS-enzootic environment alone were conducted in Laguna, Philippines. Under unfed conditions, initial signs of EUS were observed after 9 d of cohabitation and progressed into advanced stages in 10 tol6 d, whereas in exposure to EUS-enzootic environment alone, initial signs were observed in 10 d and developed into advanced stages in 15 to 20 d post-exposure. When food was given, initial signs of the disease were observed after 14 d of cohabitation and progressed into advanced stages in 17 to 20 d, whereas in fish exposed to EUS-enzootic environment alone, onset of EUS was 44 d post-exposure developing into advanced stages in 50 to 55 d post-exposure. Transmission of the disease was 100% in all treatments.

Interest in the culture of snappers, belonging to the family Lutjanidae, is increasing in Southeast Asia due to their relatively high market price. However, the fry needed for culture still comes exclusively from the wild. The anticipated demand for snapper fry has stimulated studies to develop methods of supplementing the natural fry supply. This paper evaluates the reproductive performance of wild-caught mangrove red snapper broodstock induced to spawn as part of a project to establish seed production techniques at SEAFDEC Aquaculture Department.

This paper provides a framework of conflict in small-scale fisheries and presents a case study of an island community in central Philippines. The following sources of conflict were identified: destruction of fishing gears, destructive fishing practices, and encroachment of commercial fishers into municipal waters. Mechanisms for resolution were found at the individual, group, village, and municipal levels.

The free essential amino acid levels in muscle of young Nile tilapia (Oreochromis niloticus) after feeding graded amounts of a corresponding test amino acid were measured in 9 separate experiments to determine if free amino acids indicate requirements for growth. Data were analyzed by the broken line regression method. Breakpoints for free threonine and free isoleucine were near the threonine and isoleucine requirements for growth. Breakpoints for free lysine, free histidine, and free valine were much higher than the lysine, histidine, and valine requirements for growth, respectively. Levels of other free essential amino acids in muscle behaved erratically or increased linearly as the dietary test amino acid increased. Amino acid requirements as estimated by levels of free essential amino acids in muscle did not consistently confirm amino acid requirements for growth of Nile tilapia.

Pond-reared Penaeus monodon males and females were sampled regularly over a 4 month period of length and weight measurments to the body and external reproductive organs; joining of the petasmata and the presence of sperm in the spermatophores and thelyca were also noted. Astrong linear relationship exists between body weight and length parameters, and between size of thelycum/petasma and carapace length (CL). Both the unification of petasmal endopodites and sperm presence in the spermatophores in males were first observed at Day 121 from stocking (CL 26.4 mm) while sperm was first noted in the thelycum of females at Day 125 (CL 28.6 mm). Male P. monodon with unified petasmata. In general, size were not significantly different between males and females over the culture period.

Serum samples were taken from gravid female catfish 0 to 24 h after injection of luteinizing hormone releasing hormone analogue (LHRHa) and pimozide (PIM) to monitor the serum steroid hormone levels during the off seasons (February) and the peak of the natural breeding period (August). A parallel study was also conducted to compare egg production, fertilization, hachuring and larval rates upon yolk resorption from spawn’s of hormone-treated fish. Serum E₂ levels were significantly different only with varying times after injection (PI); a marked increase occurred at 13 h, but the elevation was higher in fish induced to ovulate during the peak (16.8 ng/ml) than off season(7.7ng/ml). Hormone-treated fish showed higher serum testosterone (T) levels during the peak season (17-23 ng/ml) than those injected during the off season (10-20 ng/ml) at 4-12 h PI. Serum 17¤, 20ß-dihydroxy-4-pregnene-3-one (DHP) levels og hormone-treated fish during the off season were only about half the level (0.29 and 0.52ng/ml) of those treated with the same hormones during the peak season (0.54 and 0.9 ng/ml) at 8 and 12 h PI, respectively. Initial eggs size was larger in fish induced to spawn in August (1.54 mm) than in fish induced in February (1.49 mm). All fish ovulated when induced to spawn during the peak of the natural breeding period, but ovulation rate was only 60% when were injected during the off season. Egg production, fertilization, hatchery and survival rates were similarly much higher when gravid females were induced to spawn in August (88 eggs/g body weight, 97%, 73%, and 95%, respectively) than those spawned in February (20 eggs/g BW,36%, 20%, and 47%, respectively). Results indicate that more eggs and of better quality, higher levels of T and DHP were produced during the peak season.

Fragments of Gracilariopsis heteroclada weighing 10 g each were inserted in a polypropylene rope, suspended at different depths (25 cm, 50 cm and 100 cm below the water surface) and cultured with Lates calcarifer fingerlings (22-25 cm long and 158-252 g) in floating net cages from April to October. After seven months of culture, the specific growth rate of G. heteroclada was found to be influenced significantly (p ≤ 0.05) by the interaction of three factors: sea bass, water depth, and month of culture. Highest growth rate of Gracilariopsis heteroclada was recorded at 25 cm below the water surface during the month of April unaffected by the presence or absence of sea bass; while the lowest growth rale was observed at 100 cm during the months of September and October in the absence of sea bass. Approximately, 172 (dry) g m^-2 mo^-1 is produced from this culture system. The average length and weight of Lates calcarifer at the end of seven-month culture period was 35-39 cm and 565-741 g, respectively. Percentage weight gain/cage was 195-258, survival rate was 92-100%, and total fish production per cage was 6,780-9,637 g.