Almost killed my fish today (cold water)!

[A3M0N]

I started my aquarium earlier this year when it was pretty warm outside. I totally didn't realize how cold my water was from the outside spigot after a few days of freezing weather. Today is water change day, after refilling the tank I noticed a couple of the neons drifting down to the bottom and nearly stopped moving when I realized my mistake! I scooped out about a gallon of water and replaced it with hot water from kitchen sink (dechlorinated first), it didn't completely fix the temp but brought it up enough to revive my nearly frozen fish friends. 

I'm sure most of y'all already knew this, but for my fellow for year fish keepers: be careful with your water change temps! 

[JJenna]

I feel your stress...Every morning I check the temp in the tank because if I'm chilly the whole house is as well. We keep the temp low in the house at night but it appears the heater is keeping up!

[lefty o]

a few degrees one way or the other during a water change isnt a big deal, but a big temp change will make them shut down, and stress's them out quickly. if you(or anyone) refills with just cold water, best bet to let the water acclimate in buckets first.

[Remi de Groot]

With the high energy costs in Europe atm i had to make some choises about the heaters as well.
Not every tank is heated at the moment and at night the temp in my house drops to about 61 degrees.
Only the betta tank for now is heated.

Not heated tanks include shrimps, cory's, endlers and diamond tetra.

Any temp you've all found as really the lowest temp untill you see your fish get affected by the cold?
For now i don't see any chance in behaviour yet. Ofcourse keeping an eye on it every day.