The length-weight relationship, food habits and condition factor of wild juvenile milkfish in Sri Lanka

Contribution No. 174 of the SEAFDEC Aquaculture Department.Wild juvenile milkfish (Chanos chanos) were obtained from Negombo lagoon in September 1984. Thirty-one specimens (92–186 mm FL) had a fork length-body weight relationship of log W = −5.6083 + 3.2598 log L. These fish were caught in the early morning and had empty guts. The mean condition factor (K) was 8.7. The intestine length to fork length ratio (I) was 3.7. Two large specimens (245 mm and 340 mm FL) caught around mid-day from the ocean off Negombo had full guts. Food was mostly blue-green algae, diatoms and detritus, with a number of copepods and nematodes. These fish had K values of 11.7 and 13.6 and I values of 8.1 and 8.5. The age and the month of spawning of these fish were back-calculated using known milkfish growth rates. It seems that in Sri Lanka, milkfish spawn from January to at least November.We thank Dr. Y. Taki and Dr. H. Kohno of the SEAFDEC Aquaculture Department for critical review of the manuscript. This study was partially supported by the International Development Research Centre (IDRC, Canada) through a grant to the SEAFDEC Aquaculture Department under Project No. 3-P-81-0171 (Phase III)