I worked for several years in a public aquarium, in a few different education and animal husbandry positions. Most of my experience is with animals that are not really "pets" -- jellyfish, tidepool animals, food cultures, things like that -- but the basics are not so different.
Right now I'm keeping a planted 40-gallon long aquarium with a vaguely South American theme. I currently have small schools of three-lined corydoras, ornate tetras (Hyphessobrycon bentosi), common hatchetfish, Otocinclus, and a pair of clown plecos.