YOU SAID:

the tank goes in a fish tank with another tank in a fish tank

INTO JAPANESE

タンクは、魚のタンク内の別のタンクと魚のタンクに入ります

BACK INTO ENGLISH

The tank enters another tank in the tank of the fish and the tank of the fish

INTO JAPANESE

タンクは、魚のタンクと魚のタンクに別のタンクに入ります

BACK INTO ENGLISH

The tank enters another tank with a fish tank and a fish tank

INTO JAPANESE

タンクは、魚のタンクと魚のタンクで別のタンクに入ります

BACK INTO ENGLISH

The tank enters another tank with a fish tank and a fish tank