About 1km north of Av Central, El Níspero is a zoo set in the forest. It is home to everything from tapirs and capuchin monkeys to jaguars and more than 50 species of bird. It is also the best place to see Panama’s endangered ranas doradas (golden frogs); the strikingly colored, very photogenic amphibians are housed in the El Valle Amphibian Conservation Center on site.
As the frogs are extremely sensitive to human intrusion and climate change, their numbers continue to diminish; it's thus very unlikely you will see them in the wild. The amphibian center notwithstanding, if you are sensitive to caged animals, you should probably skip El Níspero altogether.