Development of feeding procedure for Japanese eel larvae using equipment independent of the tank body

Mass production of Japanese eel larvae is difficult because the best way to feed them has not been established. In the current procedure of feeding eel larvae, slurry type food is put on the bottom of breeding tanks and larvae eat along the bottom surface of the tanks. The bottom of such ordinary tanks needs a semicircular or hemisphere shape to help with feed efficiency and good water flow. Thus, depending on the tank shape, the food may become rotten and the water quality deteriorate. To determine an appropriate procedure and tank type for feeding larvae, it is necessary to balance the smoothness of water flow and feeding efficiency. We developed new feeding tanks which had plates set in the middle layer of the tank to feed larvae, so that the flow of water is adequate and the larvae are easier to feed. We successfully raised 40-day larvae (15.7 mm in total length) to 170-day larvae (30.3 mm in total length), and obtained one glass eel, with such feeding tanks.