To surely transfer live fishes from a water tank without hurting them and avoiding duplication.

A live-fish sucking-up device consists of a transfer hose 2, whose one end is opened in a water tank 10, a fish pump 1, which is installed in the transfer hose 2 and which sucks the water within the water tank 10 together with a live fish 20, a branch hose 7, whose one end opened in the water tank 10 is equipped with a water-passable net while whose the other end joins the transfer hose 2 at a position nearer to the water tank 10 than the fish pump 1, and a flow rate adjusting valve 6, which is installed in the midst of the branch hose 7.