Hey Sarah, I keep my 75gal african tank at 83 to prevent ich.
But the temp varies with activity in the tank, lights, vents, etc. It usually stays around 81-83.
Good point on slowly adding it to their diet, then getting rid of it. Seems logical that it should work.
*Also noted, kind of wierd they didn't take the flakes. I fed them cichlid flakes as well.