To provide aquarium for an aquarium fish capable of maintaining a constant water temperature without bulkiness even when a plurality of aquarium fish tanks are installed.SOLUTION: In a stackable aquarium fish tank 1, an upper stage and a lower stage with different dimensions are formed on the long side plate 10 and the short side plate 20, and the inner dimension of the upper stage of the long side plate 10 is The inner dimension of the upper stage of the short side plate 20 is larger than the outer dimension of the lower stage of the short side plate 20 and the outer dimension of the lower stage of the long side plate 10 is larger than the outer dimension of the lower stage side plate 10 , The inner dimension of the upper side of the long side plate 10 is larger than the inner dimension of the upper side of the short side plate 20 and the inner dimension of the upper side of the long side plate 10 is made larger than the outer dimension of the lower side of the short side plate 20. Lower legs projecting downward are formed on the lower surface of the bottom plate 30 on the respective shorter sides and the dimensions between the legs on one short side and the legs on the other short side are shorter Is slightly smaller than the inner dimension of the upper side of the side side plate 20.BACKGROUND OF THE INVENTION【課題】複数の観賞魚用水槽を設置しても嵩張ることなく、一定の水温を保つことができる観賞魚用水槽を提供する。【解決手段】積み重ね可能な観賞魚用水槽1であって、長辺側板10および短辺側板20は、異なる寸法の上段および下段が形成され、前記長辺側板10の上段の内寸は、前記長辺側板10の下段の外寸よりも大きく、前記短辺側板20の上段の内寸は、前記短辺側板20の下段の外寸よりも大きく、前記長辺側板10の下段の外寸は、前記短辺側板20の上段の内寸よりも大きく、前記長辺側板10の上段の内寸は、前記短辺側板20の下段の外寸よりも大きくする。前記底板30の下面には、下方に突出する脚が、それぞれの短辺側に形成され、一方の短辺側の前記脚と他方の短辺側の前記脚との間の寸法は、前記短辺側板20の上段の内寸よりも、僅かに小さくする。【選択図】図1
