What is the max .. temperature can fishes live (F Only tank) ??? ( in summer)

What is the max .. temperature can fishes live ???(fish only tank)((( please tell me if personal trials with high temp . )))))( in summer)
And what is bad effects of high temp. on fishes ??

 

Long term, or short term? In the summer my reef goes up past 84 during the day before I start to worry.... I don't like it to go above 86, that's when I see things starting to go bad, but mostly it's the corals that suffer. fwiw, my normal temp is 80.1º and only see spikes when the AC is off getting worked on, or on extra hot days when nothing helps.


Ideally, you should be in the 78-80 range for most tropical marine / reef fish...

In a FO system you have a lot more range, but I would avoid going above 85 for any extended period, and never change the temp more than 1ºF per hour, as that can cause all kinds of stress on fish.

As for a maximum SUSTAINABLE temperature, I would say maybe 85, and most fish would probably survive an short period (under an hour) up to about 90 (I have hit 89º in my tank for about 3 hours, it killed a bunch of coral, fish are fine) ....


but of course it's going to vary from species to species and even among specimens of the same species... I know there are fish that live in tide pools where the water temp get over 100º during the day.... and there are fish that would die in waters above 80º in short order...

 

Our FO setups run from 63*F to 77*F, depending on species. Warmer water (over 75*F) raises the bacterial count in a captive system immensely and lowers dissolved O2 concentration. It also raises a fish's metabolism unnecessarily.