His water temperature should be at least 76 with 78-82 being optimum temperature range. Most pet stores will sell a small heater, a 25w or 50w will work just fine in your tank, it will not fry your fish. Make sure to get an adjustable heater, so you can adjust the temperature to where you want it. When a betta is in water that is too cold he will lose color, become lethargic and his immune system will be compromised leaving him susceptible to all kinds of nasty things!
One hand reaches out and pulls a lost soul from harm. While a thousand more go unspoken for, they say what good have you done? By saving just this one... It's like whispering a prayer in the fury of a storm. And I hear them saying... You'll never change things...
MoonShadow Betta Fish Rescue
Saving the world one innocent life at a time