Temperature has essentially a linear effect on respiration. I don’t have my charts handy, but I would not expect more than a 20% drop in the rate from 87 to 80. That change should be rapid, n a few hours.@Jay Hemdal how long would elevated breathing from high temps take to return to normal after the temp goes down to mid 70s, once temp reaches 77 or so if fish is still breathing heavy can I rule out that being the cause?
Jay