Reproduction in the viviparous South African clinid fish Fucomimus mus

Abstract

Description of the reproductive anatomy, histology and seasonality of reproduction of the viviparous clinid fish, Fucomimus mus, was based on a collection of 227 specimens from various intertidal localities off the south-east coast of South Africa. Males produce sperm throughout the year and have an efficient sperm transmission system consisting of a muscular intra-abdominal ampulla and a prominent urogenital papilla. Paired ducts pass sperm from the testes to a highly coiled epididymus located within the ampulla. Gestation occurs within the ovarian follicles. The follicular epithelium consists of an outer squamous layer and a hypertrophied inner columnar layer. A capillary network between these layers supplies the follicle with compounds required for egg maturation and for the nutrition and maintenance of developing embryos and young. Histological sections show that sperm is stored in pockets within the ovarian stroma. Parturition occurs at regular intervals throughout most months of the year, with an apparent minimum in April. Young are 16–17mm long at birth. The number of broods ranged from one to eight and the number of young per brood from one to 24, a maximum total number of 80 young was found in the largest females. There was a positive relationship between female length and the standing stock of maturing eggs and between female length and the average number of young per brood.