Abstract
Though many works have been made on the habit of sand-eels, there are few studies on the nocturnal behavior of the fish. The present author found following facts in regard to the subject through the survey with the fish larval net (71.5cm. in diameter) in the Seto Inland Sea.
During the period from January to May, sand-eels rise to the sea surface by night, and especially abundantly in January and February (Table 1). Those fishes caught in the period up to early in April were all 1-age fish, and those caught thereafter were all 0-age fish (Fig. 2). These fishes, especially in January, were thin after spawning, and the indicator of body length-body weight relation continued to increase in its value during the period (Table 2).
From the stomach condition, it was affirmed that they keep on feeding even by night. Adult sand-eels seemed to feed seldom on larvae of the same family, at least by night, on account of the fact that they are swimming in the separate layers of the sea (Table 3).
