Java fern

Overview

Java fern (Microsorum pteropus) is the plant most people should start with. It is almost impossible to kill, tolerates a huge range of water parameters, is ignored by most fish (including cichlids and goldfish), and needs no special substrate, CO2 or high light. Those broad, leathery green fronds add instant structure to a tank, and a single plant will slowly multiply into a lush clump over a year or two.

Planting & placement

This is the key thing to get right: Java fern is a rhizome plant. The thick horizontal stem (the rhizome) that the roots and leaves grow from must stay above the substrate, in open water. Bury it and it rots and dies. Instead, tie or glue the rhizome to a piece of driftwood or rock, and let the roots grip the surface over time. See our how to plant aquarium plants walkthrough for the tying technique. It works well in the midground or background and pairs beautifully with anubias on the same hardscape.

Light, CO2 & ferts

Java fern is a low-tech plant. Low to medium light is ideal — under strong light it often develops black, crispy patches and algae on the older leaves. It needs no CO2. Because it feeds through its leaves, a liquid water-column fertilizer is more useful than root tabs; a modest weekly dose keeps the fronds deep green. Growth is slow, so be patient.

Propagation & problems

Java fern propagates itself for free. Mature leaves grow tiny plantlets (baby ferns with their own roots) along their edges and tips; once they have a few leaves, gently detach them and attach them elsewhere. You can also divide the rhizome — cut it into sections, each with roots and leaves. The usual “problem,” brown spotting, is normally just this reproduction or a buried rhizome, not disease. If you want faster, denser growth, add more light and try our CO2 for beginners guide, but it is never required.