PROBLEM TO BE SOLVED: To solve a problem in a conventional aquarium with a passage tube installed in an aquarium container, wherein the weight of water filled inside the passage tube is supported by legs and there is a case where the weight applied to the legs presses and damages a part of a bottom part of the aquarium container, and when air enters the passage tube to cause water inside the passage tube to flow out, the flowing-out water may overflow after filling the inside of the aquarium container.SOLUTION: A water tank 1 with a floating body is put in an aquarium 5, and an opening of the water tank 1 with the floating body filled with water is put upside down and lifted close to the water surface. The floating body is installed at the water tank 1 with the floating body so that the partially projecting state of the water tank 1 with the floating body from the water surface is maintained by the floating body. Aquarium fish can thereby be seen to swim inside the water tank with the floating body projected from the water surface and filled with water. When air enters the water tank with the floating body and water flows out, a floating body part allows the water tank 1 with the floating body to float on the water surface, and the water level of the aquarium 5 is lowered to prevent water from overflowing from the aquarium 5.COPYRIGHT: (C)2013,JPO&INPIT【課題】従来の水槽容器内に通路管を設置した観賞魚用水槽では、通路管内部に満たされた水の重さを脚部で支えることにより、この脚部にかかる重さが水槽容器底部の一部を圧迫し破損する場合もある。また、通路管内部に空気が入り、通路管内部の水が流れ出すと、流れ出した水が水槽容器内を満たした後に溢れ出すことがある。【解決手段】観賞魚用水槽5に浮体付水槽1を入れて、水が満たされた浮体付水槽1の開口部を下向きにし、水面近くまで引き上げる。この時、浮体により浮体付水槽1の一部が水面より上に突き出た状態が維持されるように浮体を浮体付水槽1に設置しておくことで、水面より突き出て水に満たされた浮体付水槽内部を観賞魚が泳ぐところを見ることができる。また、浮体付水槽内に空気が入り、水が流れ出すと、浮体部が浮体付水槽1を水面より浮上させて、観賞魚用水槽5の水位を下げ、観賞魚用水槽5から水が溢れ出ないようにする。【選択図】図2
