PURPOSE: To obtain the subject apparatus having compact size by vertically arranging breeding water tanks free from intermediate partition wall in plural stages, placing a level-controlling tank at one end of each breeding tank and providing a water-spraying channel, a draining hole, a draining pipe and a spraying pipe in specific state.

CONSTITUTION: Breeding water tanks 1a, 1b, 1c are arranged in vertical direction and the fresh water from a water source 2 is sprayed from a water-spraying channel 3a into the breeding water tank 1a. The bottom of each breeding water tank is provided with plural draining holes 5a, 5b, 5c and connected to each level-controlling tank 7a, 7b, 7c through draining pipes 6a, 6b, 6c. The breeding water tanks 1b, 1c are provided with water-spraying pipes 31b, 31c to spray breeding water supplied from the upper breeding water tank via the level-controlling tank of the upper breeding water tank.