Yes. I had to research the correct amount based on the size of the tank and the directions on the bottle. 5ml per 10g well I have only 1g.
I didn't use it at first because our first betta did better than the others and I didn't use any at all with him. I've always used the same bottled water with all of them and it wasn't till I started using the conditioner that they started dying in a matter of days.
I'll look for something different if I end up losing the little guy. I will replace him for my daughter.