Guppy grass (Najas guadalupensis) is a fast-growing aquatic plant species commonly known by the names – Common water nymph and Najas grass. It is popular in the aquarium hobby for its use in guppy tanks by beginner, intermediate and expert aquarists. Guppy grass provides the best hiding spots for fry, and adult fish like to swim around it. This plant is fairly hardy and versatile. It can be floated in the water column or rooted in the substrate, and it can thrive without CO2 injection as well. If you are considering adding Guppy grass to your tank, then you will definitely find this article helpful. This article provides a lot of information about Najas grass; these include background information about this plant, how to plant and care for it in an aquarium.