Morphological and gonadal histological characteristics of the silver-phase male Indo-Pacific eel Anguilla marmorata

Eight silver-phase male Indo-Pacific eels (giant mottled eels) Anguilla marmorata were collected from three small rivers on subtropical Amami-Oshima Island, Japan, and their morphological and gonadal-histological characteristics were examined. The total length, body mass and age of the silver eels were 543.8 +/- 49.3 (496-659) mm, 376.0 +/- 116.0 (282-660) g and 14.6 +/- 2.3 (11-19) years old, respectively. The silvering-related characteristics (eye index, pectoral-fin index, gut-somatic index) and reproductive characteristics (gonadosomatic index, histological stage) of the silver eels were significantly advanced compared to those of yellow eels, which is similar to other anguillid species.

Automated summary

This study examined the morphological and gonadal-histological characteristics of eight silver-phase male Indo-Pacific eels (giant mottled eels) collected from three small rivers on subtropical Amami-Oshima Island, Japan. The findings showed that the silver eels had significantly advanced silvering-related and reproductive characteristics compared to yellow eels.