Weaning of juvenile seahorses Hippocampus erectus Perry, 1810 from live to frozen food

In this study, the weaning of juvenile seahorses Hippocampus erectus from live Artemia to frozen Mysis spp. at different ages and sizes was evaluated as a means of improving commercial culture efficacy. The incremental increases in wet weight and standard length of the 42, 49, 56, 63 and 70 day-post-partum juvenile seahorses over a 14-day period were significantly different (F4, 45 = 47.359, F4, 45 = 32.108, P < 0.05), with 70 day-post-partum juveniles having highest specific growth rate (SGR) and weight gain (WG), at 5.7 ± 1.2 and 122.3 ± 18.7%, respectively. Wet weight decreased in juveniles of 42 and 49 day-post-partum at 4–6 days after being weaned. The incremental growth rate of the same age juveniles of different body sizes also differed significantly (F3, 36 = 27.185 in wet weight, F3, 36 = 19.424 in standard length, P < 0.05); the larger the juveniles, the higher their SGR and WG. The difference in body size and wet weight between the large size and small size juveniles increased after weaning to Mysis spp., with daily growth rate in wet weight 0.07 ± 0.003 g/day in large juveniles and 0.02 ± 0.004 g/day in small juveniles from 63 to 112 days post-partum. Body size and wet weight of the juveniles appear to be an important factor in deciding an appropriate time for weaning in commercial seahorse culture. The present study suggests that for juvenile H. erectus, weaning to frozen food should occur at approximately 0.54–0.70 g in wet weight or 6.59–7.46 cm in standard length.