Criteria for assessing juvenile quality of the lined seahorse, Hippocampus erectus

Juvenile quality has been demonstrated to be the key for commercial fish production. Variations in juvenile quality leading to varying growth and mortality are often encountered and well documented in many marine fish species. It is valuable to discover simple and reliable indicators for assessing juvenile quality in fish aquaculture. In this study, we established criteria for evaluating the juvenile quality of the lined seahorse, Hippocampus erectus, a Chinese traditional medicine and popular aquarium species. We raised 18 batches for 45 days from birth to determine the potential criteria for assessing the juvenile quality of the line seahorse. There was a strong and significant correlation between survival through the fifth day and that on the day 45. By comparing the ratio of trunk width at 1/2 trunk length to trunk length (TW/TL) of dead and live juveniles during the first 5 days, we found that TW/TL is a reliable indicator of the juvenile quality, with the distinct threshold of 0.190.

► We examine the early juvenile survival of the lined seahorse to predict that of late stage.
► We examine morphological characteristics to predict juvenile quality of the seahorse.
► Survival of the juveniles on the day 5 is positively related to that of late stage.
► The ratio of trunk width at 1/2 trunk length to trunk length (TW/TL) during the first 5 days is a reliable indicator of the juvenile quality.