75 degrees Fahrenheit.
Water change and black worms usually works for barbatus. I generally keep them at about 72. Got tired of watching them spawn in the discus tank (76 degrees) and not getting the eggs so I moved them into their own tank when they started 'dancing' and had the temperatures matched. Forgot to turn it down but got 100 eggs the first day and 200+ more two days later. It's a group of 12 so not sure how many females were involved.