Mosquito Fern / Fairy Moss (Azolla caroliniana)

About

Mosquito fern (Azolla caroliniana) is one of those plants that earns its place in a tank through sheer usefulness rather than drama. This tiny floating fern forms dense mats across the water surface, and its roots hanging below are excellent at pulling nitrates out of the water column, which makes it a practical ally for keeping water quality in check between maintenance sessions. It is particularly well suited to shrimp setups, where the surface mat creates a sheltered zone beneath it that shrimplets and small fry use as cover from larger tankmates. Growth can be rapid under brighter light, so it is worth keeping an eye on coverage and thinning the mat periodically to make sure light still reaches any plants growing below. No CO2 injection is needed, which keeps things simple, and the overall care demands are minimal enough that complete beginners can add it with confidence. If your tank has still or very slow-moving water and a bit of surface light, Azolla caroliniana will generally take care of itself. The main job for the keeper is managing how fast it spreads rather than coaxing it to grow at all.