Hardy and easy to care for, the widow tetra (or skirt tetra) is a schooling fish contrary to its name, comes in several colors. While the wild black widow tetra is dark in color, consider the many-colored varieties that have been captive-bred. At least six or seven specimens create a healthy, happy school of fish, but avoid housing them with smaller species (particularly those with long, flowing fins) as black widows do sometimes nip. This active, fast-moving species is a great choice for aquarium beginners.