The life history of Pterogobius zacalles (Gobiidae) was studied from 1973 to 1979 at Moura, Mutsu Bay, located at the northern tip of Honshu.Field observations were made mainly by means of SCUBA diving, and spawning behavior and early life history were observed in the aquarium.
At Moura P.zacalles inhabits shallow rocky bottoms at depths from 5 to 30 m, mostly less than 10 m.They are solitary dwellers and live around nests burrowed under stones.During their growing period at water temperatures over 10°C they hover or rest around nest stones.During the cold seasons below 8°C in water temperature they conceal themselves in the nests and rest inactive.The spawning season at Moura seems to extend from late April to late May.Spawning takes place under the nest stones.Egg masses are guarded by males.
In the aquarium one female spawned three times with the same male.The number of laid eggs and length of the long axis of the egg membrane tended to decrease as spawning was repeated.To attract the female the male hover around her, fully extending his all fins, opening his mouth and gill membranes, and slowly fanning his caudal fin.The body and all fins of the male turned black at that time, in sharp contrast with the reddish orange margins of the dorsal and caudal fins.The female did not show color change.
Eggs hatched 27 days after the blastula stage at water temperatures of 7.2°-13.7°C.Newly hatched prolarvae were 4.95 to 5.34 mm in total length.The larvae completely consumed the yolk in 6 to 9 days, when they attained 5.90 to 7.10 mm in total length.Larvae from egg masses collected from natural habitats and reared in the aquarium survived for only 31 days after hatching, reaching a maximum total length of 16.0mm.
Young fish of 3-4cm in total length were found from the middle to end of July in small schools near the bottom at the habitat of adults.Larger individuals (4-5 cm in total length) were seen either singly or in groups of two or three fish in August.In September they grew over 6 cm in total length and were observed occupying nests built under stones.In one year both sexes became fully mature, attaining total lengths of 9 to 11 cm.They changed from copepode-feeding at early stages to crustacea-polychaeta-feeding as their life mode shifted from grouping to solitary dwelling..
