Search Q10 in metabolism. For each 10C rise, you get a doubling of metabolism rates. so from 20-30C........
Also, search to see what the ambient ppm of any gas is in water as the temp rises(it will be less with higher temps in all cases).
So at cooler temps, the plants will grow slower, but this will mean it's easier to add CO2 and provide non limiting levels of CO2/ferts.
Warmer temps = less O2 in all cases.
So you start running into higher levels of ferts/CO2 required and less O2........
Cooler would be better than warmer given a choice for the plants/management. with some species of fish, 82-84F works quite well, Discus cards etc..........and a wet/dry filter set up for a planted tank(does not degas CO2 but adds O2).