FEEDING BEHAVIOUR OF JAPANESE FLOUNDER LARVAE UNDER LABORATORY CONDITIONS
S. Dou, T. Seikai, K. Tsukamoto-2000
Journal of Fish Biology, 56 (3): 654-666
Abstract:
Tank-reared Japanese flounder larvae, Paralichthys olivaceus, had a
major feeding peak in the morning and a secondary peak in the afternoon
throughout the larval development, with light being the primary factor
regulating their feeding activity. The larvae consumed rotifers in
preference to Artemia for up to 10 days, after which the food preference
shifted to Artemia. Feeding rates of the larvae prior to 10 days
post-hatch depended on prey density, but in the old larvae, feeding rates
were independent of prey density. Maximum feeding rate occurred at 19 C.
The occurrence of the attack posture, after its onset at first feeding (2
days post-hatch), increased up to 25 days, began to decrease when the
larvae prepared to settle down, then disappeared after settlement. The
occurrence frequency of the attack posture was positively related to fish
density, but inversely related to starvation duration, and occurred most
frequently at 19 C. This posture depended on prey density in larvae prior
to 10 days post-hatch, but became independent of prey density as the
larvae developed. It was obvious that, for flounder larvae, attack posture
was a behavioural character closely related to feeding and subject to
larval development and environmental factors.
(Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road,
Qingdao 266071, P. R. China. Tel.: +86-532-2879062, fax: +86-532-2870882,
e-mail: szdou@ms.qdio.ac.cn)