I have a male koi plakat betta, in a 7 gallon cube tank with a filter, but without a heater. However, I live in a tropical country with an average temperature of 30 degrees celsius during the daytime, reaching upwards of 34 degrees during particularly hot days. I heard the optimal temperatures for betta is between 25.5 to 26.5 degrees celsius. Do I need to cool my water? How do I maintain the water temperature if it fluctuates so much?