I've got a small, 6-gallon aquarium with 6 little copper rasboras that have been happy little gaffers in there for over a year and a half. :)

This summer has been especially hot here and we don't have air conditioning. The tank is not in direct sunlight and I cannot move it to a cooler area of the house where it isn't in the path of cats or small kiddos. Despite turning the heater as low as it can go (I never see the light come on while it's this low and they're right beside my home office desk), the water temperature is going above the ideal range for them during the day. They don't seem stressed, but I'd still like to bring temps back in that range. I doubt dropping an ice cube in there periodically is a good idea.

I think the light in the tank is throwing huge amounts of heat. Would it adversely affect the little guys at all to change their light timer drastically  on overnight and off during the day during the summer? Or would it be a better idea to split the ON time between early morning and late evening, giving them OFF time during the day and for a few hours in the middle of the night?

Welcoming advice or other suggestions to lower temps.