Guppy Grass Care Guide
Guppy Grass (Najas guadalupensis) is one of the most useful plants you can put in an aquarium, and one of the hardest to kill. It is a fast-growing stem plant that will happily float or root, asks for nothing in the way of CO2 or special light, and acts as a living filter while it grows. Fry keepers love it because a loose clump turns any tank into a nursery. If you are new to live plants, this is the one we tell people to start with.
Quick Stats
- Scientific name: Najas guadalupensis
- Type: Fast-growing stem plant (floats or plants)
- Care level: Easy
- Lighting: Low to high; grows under almost anything
- CO2: Not required
- Growth rate: Very fast
- Placement: Floating, or planted in the background
- Temperature: 68–86°F
- pH: 6.0–8.0
Planting and placement
Guppy grass does not care how you keep it. Let it float and it forms a dense tangled mat at the surface; push the stems into the substrate and it roots and grows upward instead. Most keepers do a bit of both. There is no rhizome or crown to worry about, so you can plant it, bury it, or leave it drifting and it will be fine either way.
It is brittle by nature, and that is a feature, not a flaw. Every fragment that breaks off can grow into a new plant, which is how a single portion quickly becomes a tankful. The only real maintenance is pulling out handfuls when it gets too thick.
Light, CO2, and nutrients
This plant will grow under a desk lamp. Give it more light and it grows faster and denser; give it less and it simply slows down. No CO2 injection is needed. It feeds straight from the water column, pulling nitrate and ammonia out as it grows, which is what makes it such a good natural filter for a new or lightly-stocked tank. In a sparsely planted setup a little liquid fertilizer keeps the color a bright fresh green, but it is not required.
Why fry keepers love it
A floating clump of guppy grass is the single best fry refuge there is. Newborn livebearers and egg-scatterer fry dive into the tangle where adult fish cannot follow, and the dense growth also harbors the tiny organisms (infusoria) that fry graze on in their first days. If you keep endlers, guppies, or swordtails and want some fry to survive without a separate tank, drop in a handful of guppy grass and let nature do the rest.
Propagation
There is nothing to it. Snip or pinch off a length of stem and it is already a new plant. Drop the trimmings anywhere and they keep growing. Trade the excess, spread it to other tanks, or feed it to herbivores; you will never run short.
Ordering from us
Plants ship wrapped damp in an insulated box and travel well in moderate weather. Guppy grass is fast and forgiving, so even if it arrives looking a little ragged it bounces back within days of going into your tank. Rinse it on arrival, remove any loose bits, and either float it or plant it. As with any new plant or livestock, a quarantine or a quick dip is good practice. See our Shipping & Acclimation and Water Chemistry guides for details. Questions? Email help@jojoaquatics.com.
— The JoJo Aquatics team, Key West, Florida
