15 Tips for Cultivating a Thriving Java Fern
Java Ferns are one of the easiest and most rewarding plants to grow in an aquarium — if you know how to treat them right. Whether you’ve got a standard Java Fern or a fancy Windelov or Narrow Leaf variety, the basic care is the same. We’ve grown them in multiple tanks over the years, and here’s what we’ve learned about keeping them healthy and thriving.
Why Java Ferns Are Awesome
Java Ferns (Microsorum pteropus) are tough, low-maintenance, and look great in just about any freshwater tank. Fish love them — especially cichlids and South American species — because the broad leaves provide cover and hiding spots. Plus, most herbivorous fish tend to leave them alone, which is a big win.
They don’t need special substrate or CO₂, and they’re happy in tanks as small as 10 gallons. They're also great for aquascaping and mixing in with other plants.
How to Keep Java Ferns Happy
1. Don’t plant them in substrate.
This is the #1 mistake we see. Java Ferns don’t grow in the soil — they attach to rocks, driftwood, or decorations. If you bury the rhizome (that thick, horizontal root), it’ll rot. Instead, tie the plant loosely to a piece of wood or rock using thread or a zip tie. Once it starts to root on its own, you can remove the tie.
2. Give them time.
They’re slow starters. We’ve had ferns that took a few weeks to show any signs of growth. That’s totally normal. Once they settle in, they’ll start pushing out new leaves — sometimes with little black bumps where baby plants (called plantlets) will grow.
3. Watch the water conditions.
Java Ferns do best in:
- pH: 6.0–7.5
- Alkalinity: 3–8 dKH
- Temp: 72–82°F (22–28°C)
They’re super adaptable, but avoid adding CO₂ — they don’t need it and too much can actually hurt them. They also thrive in brackish water (a little salty), so don’t worry if you’re running a lightly salted tank. Just keep salinity under 1.009.
4. Light them gently.
These ferns like low to moderate lighting. Too much light — especially from strong incandescent bulbs — can scorch the leaves. If you see brown spots, it might be light burn. Aim for 1.5 watts per gallon using bulbs in the 5,000–7,000K range. They’ll do just fine even in dim setups.
5. Don’t panic over black spots.
Black veins and bumps are totally normal — they’re not signs of disease. In fact, those bumps are often baby ferns getting ready to grow.
6. Handle with care.
If you need to move your Java Fern, be gentle. They don’t love being relocated and might sulk for a while (a.k.a. stop growing). Just give them time — they usually bounce back within a few weeks.
7. Fertilizer isn’t always needed, but…
If your fern isn’t growing or the leaves look dull, it might need a boost. Use a liquid fertilizer that contains iron — it helps keep the leaves bright green. We’ve had tanks where the ferns thrived without any fertilizer, but others definitely needed a little help.
8. Plan your layout.
Java Ferns can grow pretty tall — up to 12 inches — so plant them in the mid or back of the tank. They pair well with almost any other freshwater plant, so feel free to mix them in with Anubias, crypts, or floating plants.
In short, keep your Java Ferns tied to something solid, don’t bury the roots, and give them low light and clean water. They’re one of the most forgiving plants out there and a great choice for beginners and seasoned aquarists alike. Once they take off, they’re just plain fun to watch grow.