Published online by Cambridge University Press: 06 July 2012
Hatchlings of clown loach (3.8 mm in total length, TL) are pelagic. Whenreared at 26−28 °C, they become benthic 3 days after hatching (dah), when their swimbladder is inflated. The fin development sequence (pectorals < caudal < dorsal = anal < pelvic) is typical of the clade Ostariophysi. All fins andfinrays are fully elongated at 20 mm TL, but the finfold persists until25 − 26 mm TL (start of juvenile stage). Melanophores appear at 3 dah,they form a 5-bar pattern at 5 dah, then two bars (III and V) vanish progressively,producing at 26 mm TL the 3-bar pattern that is typical of adults.Throughout the ontogeny, the pigment pattern exhibits a structural regularity (bars spacedat regular intervals), which is interpreted in a functional perspective by reference tothe maintaining of crypsis and signalling throughout. Exogenous feeding commences at 4 dah(5.5 mm TL). Food intake (FI) increases rapidly, from 6%wet body mass (WM) at 5.5 mm TL to >20%WM in fish > 7 mm TL. Gut evacuation rate(Rg) increases with increasing meal sizeand fish size, as a result of gut coiling (from 8 to 15 mm TL), and ishighest at 11 mm TL (about 10% WM h-1 in fishfeeding maximally). The allometric increase of FI andRg during the early larval stages isaccompanied by increasing capacities for growth, so early sizes differences amplifyrapidly during the ontogeny. Nevertheless, growth remains slow (mean of 0.4 mm TLday-1 from 4 to 29 dah; 0.9 mm TL day-1for top growers). By contrast, unfed fish display long resistance to starvation (until14−15 dah). The combination of slow growth and long resistance to starvation is discussedin respect to the reproductive phenology of the species, as the capacity of makingmetabolic economies prevails over fast growth for seasonal strategists spawning mainly atthe start of the rainy season.