Larvae of the Siamese fighting fish Betta splendens were reared on the mass-cultured small freshwater rotifer Brachionus angularis Laos strain (UTACLao), Paramecia sp., and Artemia as live food sources. Larvae fed live food were found to have a significantly high survival rate (97.5-100%) 18 days after hatch (DAH) in comparison to the control unfed larvae, which died by 12 DAH. Rotifer-fed larvae were found to grow faster than paramecia-fed larvae. The fastest growth rate was observed in larvae fed a combination of rotifer and Artemia, with growth in these larvae increasing by 282% by 18 DAH [total length (TL) 11.3 ± 1.2 mm] relative to body measurements taken 3 DAH. The next fastest growth rate was observed in rotifer-fed larvae, with a 158% increase in growth observed by 18 DAH (TL 7.6 ± 0.5 mm). The paramecia-fed larvae were found to grow by only 54.3% (TL 4.6 ± 0.1 mm) during the same period.
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.
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