Thanks, that would work

If im right the ground space is 36x18 with a height of 16 inch

That is approx. 90x45 on the bottom with a height of 40 cm.

If i'm right, that is a great size to keep them in.
My experiece with the Phyllobates species is that they tend to breed better as a group then in pairs,
they are verry social so a group won't pose any problems.

I should say that in this size you can keep a breeding group of around 6-7 terribilis.
Make sure they can all have a place they can hide now and then.
A well planted viv is something they seem to like here as well.

Don't worry about seeing them, you will

Last advice would be, take a group with more males then females,
they stimulate eachother to breed.

Good luck finding some nice ones,
prefered to mix in different bloodlines