R. Vanzolinii is a beautiful dart frog from the thumbnail group that is endemic to Peru and Brazil. Generally, they are a bold, active frog that does quite well in captivity. In terms of tank size, a 20 gallon vertical tank would be sufficient. Although, larger tanks are always better. Make sure to include a good amount of both vertical and horizontal space as these frogs are semi-arboreal and will spend time climbing and on the forest floor.
Temperature should range from the upper 60's to the upper 80's generally staying towards the middle of that range. Humidity can be upwards of 100% although air flow is an important part of keeping a clean tank. Including bromeliads, cork bark tubes, and a good amount of vegetation within the tank will help keep the frogs feel safe to explore the tank regularly.
Their diet will primarily be fruit flies that should be dusted with a high quality vitamin/calcium supplement about 2-3 times per week. Water dishes aren't necessary if you include bromeliads that hold water in their axils, otherwise some film canisters with a suction cup can work as a great water dish. Leaf litter is also another essential part of their tank. Leaf litter serves as hideouts on the forest floor but it also provides food for the microfauna that should be the other part of R. vanzolinii's diet. Microfauna such as springtails and isopods are essential components of a great tank because they not only eat the dead rotting material, but they also are a great source of food for your frogs.
R. vanzolinii are said to be monogamous and will pair off to breed. I've found that one male and two females will work out in some cases, although start with just one male and one female. In order to promote breeding behavior feed heavier and water more often. If successful you'll notice the male calling from an egg laying site and, if the female is receptive, she'll follow him around and stroke his back sometimes. Since vanzolinii are non-obligate egg feeders the parents will completely raise the young from start to finish. This is the best way for beginners to breed these frogs.
Overall, R. vanzolinii are striking frogs with a bold attitude and beautiful call that are some of my favorite frogs in my collection. I'd suggest them for the intermediate hobbyist with at least some experience with thumbnails.