Hi I have had Franks Aquarium Butterfly loaches in my Discus tank but they did not like 84, Most will be ok and survive at 80 but mine did not move around a lot. They are also very good at eating eggs. My Discus would push at them to move and they did at first, but learned real quick how to get around that.
I love, Sids for there activity during the day and through-out the tank.