| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-stage type aquarium increased in the volume of the aquarium by intactly utilizing a conventional aquarium and further combining the aquarium with an aquarium in the upper stage when a kept goldfish is grown up or the number of the goldfihes is increased. SOLUTION: This two-stage type aquarium is obtained by combining an aquarium 1 in the lower stage with an aquarium 2 in the upper stage. The aquarium 2 having the ceiling and the opened lower part is housed in the aquarium 1 in the lower stage and the space in the ceiling part of the aquarium 2 in the upper stage can be kept in a vacuum state to thereby increase the level of the water surface 7. Furthermore, goldfishes 5 are capable of going and coming between the aquarium 1 in the lower stage and the aquarium 2 in the upper stage and swimming about.
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