aquarium fish expose to daily temp fluctuation?

[Rocksor]

I was more referring to my other indoor aquariums, I was thinking maybe 1 primary heater always set at 77 degrees, while a secondary at 79 and will turn off during the night with a timer, and changing to 75 and 77 respectively in the winter. so the worst temp fluctuation can be no greater than 2 degrees. that may help trigger natural seasonality and spawning behavior in the fish?

again I wasn't seeing a pressing or super valid need for me to implement such, it was just an interesting idea that popped into my mind

I would just use a single inkbird heater controller for both heaters. It's much easier to make temperature adjustments, and you can adjust how much of a deviation from your ideal temperature when you want the heaters to turn on. For instance, I have my controller set to 73F with a 1 degree variance, so when the temperature drops to 72F, the heaters are turned on (the heaters are set to turn off after reaching 80F). So in your case, you can set the degree variance to 2 degrees with the ideal temperature being 77F.

 

[FahakaPapa]

In the wild fish will move to the areas where the water temp is most favorable to them. I know this from fishing Lake of the Woods here in Canada (Ontario mainly). As summer progresses, the fish always head towards the reefs in the deeper areas of the lake where they can dive down to cooler water. As summer ends they begin to move back onto the more shallow reefs. As for tanks.. as mentioned, it's much better to keep the temp as stable as possible.