So just how critical is temperature?

Tom Owens, you are not understanding what I said.

A 10 degree swing from the norm, say 78 degrees is tolerated much easier than a swing in the other direction. Not a daily swing. Not an hourly swing. Not even a weekly swing of 10 degrees.

If you keep your livestock for an extended period of time at constant 68 degrees you will not suffer the kind of losses you will if you kept your tank at a constant 88 degrees. I'll let you figure out why. 10 degrees swing/difference from the norm. 68 degree water when shipping in the winter is not uncommon at all.

Like I said before but some people are just taking things out of context. Stable temp is much more important. I didn't say a word about daily temperature swings.