PURPOSE: To provide an inexpensive water basin for aquarium fish, easy to handle, capable of easily conducting drainage operation through a connected series thereof, needing no special water supply/drainage implements, etc.

CONSTITUTION: A pair of penetrating holes 12A, 12B are arranged at a specified height on each sidewall 11C-11E of a water basin for aquarium fish 11. Generally, the holes 12A, 12B are plugged; however, when water supply/drainage is to be made, these holes are fitted with adapter pipes 15. A hose 14 is connected to the projected end of each of the pipes 15 to conduct water supply/ drainage. The water supply/drainage can be easily made while keeping water level at a specified height. This water basin, having the above scheme, is easy to connect with other water basins.