Good morning Cheri. They're quite bold, actually. They will often be in front of the enclosure, which makes it easy for me to take pics. They are VERY active, too, from early morning (6:30/7 - when my timer turns their light on), and will be out until 7 at night, too. The male started singing 4 days after we got them and put them in their enclosure.
They are very social, and from what the breeder tells me, are happier in pairs or groups. My pair follow each other all day.
As for their size, my male is about 13 centimeters, and the female, 15 cm. That is their adult size.
I got them from Understory Enterprises. Here's a link to the vents page:
Understory Enterprises Inc. - Ranitomeya ventrimaculata
Eric