The Life History of the Gobiid Fish, Luciogobius elongatus

Luciogobius elongatus Regan is a relative of Luciogobius guttatus Gill occurring along the coast of Japan. It is a small elongate gobiid fish grows to 40mm in full grown size. It had been collected from some localities in the central and southern Japan. Recently, over 320 specimens of the fish were collected from Nomo and Kawahara both near Nagasaki (Lat. 32°40.5' N, Long. 129° 50.5' E). The habitats of the fish were restricted to the areas of pebbles deposited over the rocky hollows in the upper intertidal zone in several decacentimeters depth. At low tide, the sea water of the habitat was drained off and the pebble surface was exposed in the air for several hours, but the pebbles lying in the inner part of the deposit were moistened by slight standing water on the rocky hollow. The fish burrowed among the moistened pebbles, measuring about 2 cm in size, at about 20cm depth. It fed on the tiny gastropod, Brachina glabella, ostracods, amphipods and creeping copepods. Five egg masses of the fish were collected from the two habitats in the coast of Nomo during June to July 1972. Each egg mass was attached on the underside of a rather large pebble lying in the pebble deposit at about 20cm depth and guarded by a male parent. The egg number ranged from 24 to 77 in 5 egg masses, and each egg mass comprised the eggs in the same developmental stage. The eggs were spindle-shaped and ranged from 1.52 to 1.78mm by 0.64 to 0.71mm. The newly hatched larvae, provided with from 44 to 45 myomeres, ranged from 2.75 to 3.10mm in total length. About 100 larvae hatched out of the 2 egg masses collected were kept in a 30 liter plastic aquarium and reared for about one month. The larvae were first fed with the mixture of the larvae of the oyster, Crassostvea giges and the rotifer, Brachionus plicatilis and next with the mixture of the nauplii of the brine shrimp, Artemia salina, and the splash copepod, Tigriopus japonicus. The larvae first spent the planktonic life for about 20 days and entered into the bottom life at the body length of about 13mm at the early young stage. From the examination of the collected specimens, the spawning season of the fish in Nomo seemed to extend from early May to early August and the fish seemed to grow to the mature length of about 30mm in a year