Temperature For Goldfish

In California we’re currently going through a heat wave. As goldfish are a cold water fish. Would it be best to let the water in tank fluctuate in temperature or heat the water enough to prevent those fluctuations?

 

What kind of goldfish?

 

Fancy. Ranchus, ThaI Orandas.

 

Anything below 70 is good.

 

Agree high 60's low 70's is ideal but they will be ok at room temp for short periods of time. Honestly I don't see a tank fluctuating rapidly enough to harm them unless its a little tank.

 

They go through fluctuations naturally from day to night. Pond or aquarium? Don’t heat the water to keep it stable. If the water gets too warm you can put a fan by the tank, float frozen water bottles but you’ll have to watch the temp.