Cold water... Hot water... Seems like it doesn't matter

[Nicho]

I live in the Caribbean, and in my country the average temperature is usually 26 °C (78.8 °F). It never snows or has extreme heat, and i've never, ever, seen anyone using heaters on their tanks. People keep goldfish and koi and they're fine, same temperature as the tanks they keep tropical fish (without heaters) and they also seem to be fine.

I guess my real question is uhh... How does cooler water affect tropical fish? I know that heat speeds up activity, growth and digestion in coldwater fish, but can cool temperatures kill them/shorten their lifespan?

 

[jcolon]

I live in the Caribbean, and in my country the average temperature is usually 26 °C (78.8 °F). It never snows or has extreme heat, and i've never, ever, seen anyone using heaters on their tanks. People keep goldfish and koi and they're fine, same temperature as the tanks they keep tropical fish (without heaters) and they also seem to be fine.

I guess my real question is uhh... How does cooler water affect tropical fish? I know that heat speeds up activity, growth and digestion in coldwater fish, but can cool temperatures kill them/shorten their lifespan?

Depends on how "cool" the water gets. In the tropics extreme temp drops isn't generally an issue to worry about. However, where I live, i've literally had 15-20 degree(F) swings overnight. In a non heated tank, letting temps go from 70 down to 50's can lead to stress / illness.