The morphological development, including the fins, body proportions and pigmentation, of laboratoryreared larval and juvenile Pangasianodon hypophthalmus was described and their behavioral features were observed under rearing conditions. Body lengths (BL) of larvae and juveniles were 3.0 ± 0.2 (mean ± SD) mm just after hatching, and 12.9 ± 1.1 mm on day 13, reaching 23.4 ± 1.8 mm on day 25 after hatching. Aggregate fin ray numbers (for caudal fin, principal soft ray number) attained their full complements in specimens larger than 12.8 mm BL. Notochord flexion began in yolksac larvae on day 0 (10.5 h after hatching), with teeth buds and barbels appearing with jaw formation in yolksac flexion larvae on day 1. Melanophores on the body increased with growth, with a broad vertical band forming on the lateral line and an oblique band extending from above the pectoral fin base towards the forepart of the anal fin during the postflexion larval and juvenile stages. Body proportions became relatively constant in juveniles, except for maxillary barbel length (MBL), which continued to decrease. Yolksac flexion larvae started feeding on day 2 with the onset of intense cannibalism. Yolks were completely absorbed by day 3, and cannibalism ended by day 6. Subsequently, fish displayed a schooling behavior with growth, preferring relatively dark areas during the juvenile stage.

The morphological development, including the pigmentation, body proportions, fins, and survival rate for 30 days after hatching, of laboratory-reared larval and juvenile Hypsibarbus malcolmi is described. Body lengths (BL) of larvae and juveniles were 2.0 ± 0.2 (mean ± SD) mm at 1 h after hatching (day 0) and 9.2 ± 0.6 mm on day 16, reaching 12.1 ± 0.9 mm on day 30. Yolk volume decreased linearly, with the yolk being completely absorbed by day 3 in all preflexion larvae (all specimens [3.2 mm BL). Feeding was observed on day 2 in fish which had rapidly undergone complete yolk absorption following mouth and anus opening on day 1, and on day 3 in all remaining fish. Myomere numbers were 20-21 ? 11-12 = 31-33, although they were not clearly visible in juveniles.Melanophores were few on the body during days 0-2, but increased with growth and covered the entire upper dorsal body surface during the juvenile stage. Body proportions tended to become constant in juveniles. Notochord flexion began in larvae[5.2 mm BL on day 8, and was completed in larvae [8.4 mm BL on day 14. Specimens with full fin ray complements were initially observed on day 22 (10.4 mm BL in juveniles). All specimens[11.5 mm BL had attained the juvenile stage. A high survival rate of 92.7% was estimated on day 30.

The predation of cultured larval fish by water insects presents a serious issue for aquaculture development in rural areas of the Lao People's Democratic Republic (Lao PDR). In this study, the species composition of predatory water insects was monitored in a fish nursing pond. Laboratory predation experiments were then performed to examine the predation potential of water insects on 3 major cultured fish species, including Barbonymus gonionotus, Cirrhinus cirrhosus, and Cyprinus carpio. Anisops spp. was considered to have the highest impact on mortality by predation in Lao PDR. It was estimated that Anisops bouvieri can prey on 10.4-46.7% of larval fish within 24 h under standard rearing conditions recommended by FAO.

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