What happens when you keep a tropical fish in colder water?

what happens when you keep a tropical fish in colder water? I keep hearing how fish die in temps that they’re not suppose to, but what happens when they live.

 

For one, they are more susceptible to disease.

 

Most fish will just become lethargic and inactive. Theyll eat less, theyre metabolism slows. They may come down with ich, disease outbreaks as theyre not going to be as healthy, and more than likey after a period of time they would start dying off.

Once in a while we have a LONG power outage, like a week or two. My tanks will dip to 60ish but Ive never had a problem. I MIGHT lose a neon here or there, but nothing else. But this is short term. In the long term, it would be detrimental to their overall health.

 

More susceptible to disease (as stated above), less tempted to eat, less active, smaller lifespan, etc.

 

Ironically, though, warmer temps make fish age faster. The cooler temps make them age slower. So even though cooler temps are dangerous and 99% of the time cause problems, this is why there's always that one exception, that one person who never used a heater and their fish lived forever.