PROBLEM TO BE SOLVED: To provide a method for growing and / or culturing organisms living in a freshwater aquarium or a saltwater aquarium, which can reduce nitrite generated through organisms in an aquarium (including aquaculture pond). SOLUTION: A method for growing and / or culturing an organism that lives in a fresh water tank or a sea water tank is a method for purifying water and / or filtering a mixed gas of oxygen and hydrogen obtained by electrolyzing tap water or fresh water. The purifying means or the purifying means by releasing the mixed gas into an ornamental or aquaculture seawater aquarium having water purifying means and / or a filtering means. Even when a filtering means is used, it is characterized in that nitrous acid generated through organisms in the water tank is reduced in accordance with the amount of the mixed gas released and the passage of time. [Selection diagram] None【課題】水槽（養殖池含む）内の生物を介して生じる亜硝酸を低減させていくことが出来る淡水水槽又は海水水槽に生息する生物の生育及び／又は養殖方法の提供。【解決手段】淡水水槽又は海水水槽に生息する生物の生育及び／又は養殖方法は、上水又は淡水を電気分解することで得られる酸素と水素の混合ガスを、水の浄化手段及び／又は濾過手段を有した鑑賞用又は養殖用の淡水水槽に放出させるか若しくは該混合ガスを水の浄化手段及び／又は濾過手段を有した鑑賞用又は養殖用の海水水槽に放出することで該浄化手段又は濾過手段を用いた場合であっても、該水槽内の生物を介して生じる亜硝酸を放出される混合ガスの量及び時間経過に準じて低減させることを特徴とする。【選択図】なし
