This study is among the very first to analyse the interactions between feeding level, prey density and fish density in fish larvae. It provided evidence that fish density and prey density, rather than feeding level, govern the growth of P. hypophthalmus larvae, whereas their survival is influenced to a greater extent by the feeding level than by prey density, and little affected by fish density. The results also provide information on how the rearing and feeding strategies can be defined in respect to production constraints, in terms of survival, growth or food conversion. In particular, the study permitted us to model the relationships between food intake and fish size during the
larval stages of P. hypophthalmus, thereby giving the opportunity of adjusting feeding charts to fish size, which can be rapidly obtained from fish samples. The maximal meal size is low during the early feeding stages (12% WM at 5.5 mm TL and 0.72 mg), but increases rapidly as it amounts to 22 and 26%WM,respectively at 6.0 and 6.5mm TL (corresponding WM of 1.2 and 1.6 mg). From 7 mm TL onwards, meal size starts decreasing in a curvilinear way, and it amounts to about 10% WM at 15 mm TL (WM of 25 mg). Based on stomach residence time (b3–4 h at 29 °C in 6.5–7.0 mm TL fish; E. Baras and Y. Moreau, unpublished data), the daily food intake can be 6 to 8 times higher than meal size, thus 155–205% WM. These estimates concur with those obtained during independent experiments where the food intake of cannibals was estimated from the number of siblings consumed during 24 h (i.e. up to 203% WM in a cannibal of 5 mg WM; E. Baras, unpublished data). They also support the “empirical” recommendation of Hardjamulia et al. (1981) that larvae should be fed
250% WM per day during the first feeding days.
This study is among the very first to analyse the interactions between feeding level, prey density and fish density in fish larvae. It provided evidence that fish density and prey density, rather than feeding level, govern the growth of P. hypophthalmus larvae, whereas their survival is influenced to a greater extent by the feeding level than by prey density, and little affected by fish density. The results also provide information on how the rearing and feeding strategies can be defined in respect to production constraints, in terms of survival, growth or food conversion. In particular, the study permitted us to model the relationships between food intake and fish size during thelarval stages of P. hypophthalmus, thereby giving the opportunity of adjusting feeding charts to fish size, which can be rapidly obtained from fish samples. The maximal meal size is low during the early feeding stages (12% WM at 5.5 mm TL and 0.72 mg), but increases rapidly as it amounts to 22 and 26%WM,respectively at 6.0 and 6.5mm TL (corresponding WM of 1.2 and 1.6 mg). From 7 mm TL onwards, meal size starts decreasing in a curvilinear way, and it amounts to about 10% WM at 15 mm TL (WM of 25 mg). Based on stomach residence time (b3–4 h at 29 °C in 6.5–7.0 mm TL fish; E. Baras and Y. Moreau, unpublished data), the daily food intake can be 6 to 8 times higher than meal size, thus 155–205% WM. These estimates concur with those obtained during independent experiments where the food intake of cannibals was estimated from the number of siblings consumed during 24 h (i.e. up to 203% WM in a cannibal of 5 mg WM; E. Baras, unpublished data). They also support the “empirical” recommendation of Hardjamulia et al. (1981) that larvae should be fed250% WM per day during the first feeding days.
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