ミジンベニハゼの産卵,卵発生および仔魚

Abstract

A pair of the mature gobiid fish, Lubricogobius exiguus were collected with a shrimp trawl net from the coastal zone of Nomozaki near Nagasaki City in the night of the 8th of October, 1962. The pair fish, female was 30mm. in total length and male 28mm., had been kept in a table aquarium, provided with shell nests, for 52 days (Fig. 1). During this rearing period they spawned 6 times at 7 to 11 days intervals. In the spawning of this gobiid fish, with no nuptial color, the phase of prespawning behavior which had been recognized evidently in the spawnings of other gobiid fishes, e. g. Gobius minutus (Guitel, 1895), Bathygobius so-porator (Tavolga, 1954) and Pterogobius elapoides (Dotu and Tsutsumi, 1961), did not appear-ed. The order of nest preference which was given to nests was Ostrea (Crassostrea) gigas, Mactra sulcataria, Atrina (Servatrina) pectinata, laid on the aquarium-bottom, and the side glasses of the aquarium (Fig. 2, A). The glasses were used as nesting site when the shells were removed entirely from the aquarium. These characteristics of the spawning behavior show a particular form of the spawning of small gobiid fishes as L. exiguus and Typhlogobius californiensis which seem to live in a few members and usualy in a pair at the natural habitat. The spawned eggs were deposited in the nest in one layer (Fig. 2, B). The number of eggs of one brood was enumerated as about 1, 000. The egg was demersal attaching one with a bundle of adhesive filaments at the basal end. It was ellipsoid, with a large perivitelline space, 1.04mm. in long axis and 0.39mm. in short axis (Fig. 2, C: Fig. 3, A, B, C, D). The incubation period was about 4 days 12 hours at about 24°C. The newly hatched larva was 1.79mm. in total length (Fig. 3, E).