Taking up the hobby with my daughter who selected Glofish (genetically altered Zebras) as her fish of choice. Because Zebra Danios can handle such a wide range of temperatures I'm thinking about not getting a heater. When I had an aquarium as a kid a heater would often fail in the "on" position and the result would be fish soup. There would be a slight fluctuation of 4-5 degrees between the daytime winter temp and the nighttime winter temp (we like it cooler for sleeping). During the summer months the temperature is even (though slightly warmer). Is this a problem? Would the cooler evening temps stress the fish, or would that just be similar to natural conditions where presumably the temp drops a little when the sun goes down?
