Effect of riverbed substrates on the formation of spawning male school in Japanese minnow Phoxinus lagowski
Japanese fat minnows form spawning schools composed of spermiating males, at the gravel bottom in streams. Males were placed in tanks with various substrates at the bottom: gravel, mud, stone, or concrete. Water in the tanks was drawn to a Y-maze tank to observe behavioural responses of the males. The males stayed in water from the gravel- laid tank. Results suggest that gravel is an important factor to induce formation of the spawning school of the minnow.