The only way you will successfully do this is to remove the loach to QT tank, and SLOWLY raise the temps. Now depending on the severity of the ich, you may have a problem here. Heat in the range of 87 F is required, and kept that way for 2 weeks after the last spot of ich is seen.
Now as I mentioned the problem is that if he is covered heavily in ich, you are in a battle against time. I would start with 2 degrees for every 12 hours. You may have to up that to 2 degrees every 6 hours. Also you will need an airstone or lower the level of the water to create more splash. Esp important for a cooler water loach. You can't do this in your main tank because of the goldies. If you can't set up a QT tank, ( 5 gal rubbermaid container with a small filter and airstone would work, and obviously a heater, then try treating with meds at half strenght. I would definately do the QT if at all possible.
