Patterns of ontogenetic changes in relative growth in the precocial cyprinid, bitterling (Rhodeus sericeus)

In order to describe patterns of relative growth during the early life-hist ory of the bitterling Rhodeus sericeus (Pallas, 1776), we examined 21 morph ometric characters. These were expressed in 24 indices as a percentage of s tandard length (SL) and head length (HL) respectively. and divided into gro ups according to their pattern of relative growth. Nine characters exhibite d isometric growth (relative proportion did not change with increasing SL). Eleven characters exhibited positive allometric growth (relative proportio n increased with increasing SL) and four negative allometric growth. Stabil isation of characters may occur when bitterling reach sexual maturity, howe ver some may continue to grow allometrically during the adult period. Cauda l peduncle depth factor and body shape factor were employed to describe cha nges in morphological indicators of locomotor activity. Both factors exhibi t steep allometric growth in specimens with remnants of finfold, gradually stabilizing in immature specimens without finfold, and isometric growth dur ing adult period. Following our results and examination of data from the li terature we conclude that bitterling, although a species with a precocial f orm of development, still retains a larval period. However, its duration is short compared to other cyprinids. Allometric growth is a typical feature of the entire life-history of bitterling and cannot be used as an indicator of the transition from larval to juvenile period.