Some cold water fish species that can tolerate slightly warmer water, such as white clouds or zebra danios, may be able to cohabitate with some tropical fish species that prefer cooler temperatures, such as platies or guppies.
Can you put cold water fish in a tank that has had tropical fish?
It is generally not advisable to put cold water fish in a tank that has had tropical fish. Cold water fish require a lower temperature range than tropical fish, and if the tank is not able to maintain the cold water temperature, the cold water fish could become stressed and eventually die. Additionally, some tropical fish may exhibit aggressive behavior towards cold water fish, which could further stress the cold water fish and even lead to their demise.