Both your fish come from tropical regions so they require warm water to live in. You should research the minimum and maximum temperature the fish required to live in comfortably. The fish you are keeping would probably require a minimum temperature of 24 to 25°C, and a maximum of 30°C, give or take a little. Most people would require heater, unless of course you live in a very warm climate. Having said that, many people who live in the warmer climates have air conditioning so you would probably still need some kind of heating in your tank. Hope that answers your question