The scientific name is taxiphyllum barbieri, but it’s commonly called Java Moss. (There are a few older names for it, like vesicularia dubyana, but t. barbieri is now the accepted name.)
Java moss has little, delicate, branching green stems with very tiny, oval leaves. It usually grows between 3 – 10cm thick, depending on tank conditions.
But here’s the kicker: It’s one of the best plants for beginners, and is nearly impossible to actually kill.
It can be dark or bright green, depending on recent new growth. When growing above water, t. barbieri will produce much larger leaves to capitalize on the CO2 available in air.
Like other mosses, Java moss has no root system. Instead, it spreads via rhizoids — brown, hairy, filament-like structures. (Rhizoids are also what give Java Moss its famous capacity to “grip” the surface it’s growing on.)
Ideal Conditions for Java Moss
As with (almost) any other aquatic plant, CO2 and high light will cause java moss to grow faster.
But, here’s the deal: you don’t need it.
This plant is likely impossible for you to kill. It doesn’t even need planting — it will quite happily grow free-floating.
Technically Java Moss does need light. However, any light at all will suffice. Any decent aquarium light is very adequate. Of course, higher light will push faster growth.
It gets even better: Java Moss also doesn’t require a heater. It will survive in temperatures ranging as low as 65º F, and up to 86º. (18º-30º C) It’s worth noting that t. barbieri grows faster in cooler temperatures, so if you’re looking for fast growth, leave the heater out!
It is important to trim it properly — as it grows thicker, the interior portions of the plant can be cutoff from light and the flow of water.
If that happens, it’ll turn brown as it dies, and it can even cause the entire plant to lose its ‘grip’ on its surface.
As with all mosses, algae commonly grows on it. This is even more prevalent in slow-growth conditions (low light/flow/nutrients). To ensure optimal growth, gently agitate the stems during cleaning to prevent any buildup.
Propagating Java Moss could not be easier. Literally cut off a portion of the stems, and leave them floating. Those stems will continue growing without any issues! (Be warned: it can take over your tank if you leave bits floating around!)
And it gets better: having a ton of t. barbieri in your tank will pull a significant amount of nitrates from your water, increasing the time between required water changes.
Java Moss is so good at removing nitrates you’ll want to ensure you’re dosing ferts, if you have other slow-growing plants in your tank, like Anubias.
This plant has no conflicts — it’s great for shrimp tanks, fish tanks, and everything in between. (Fry love this stuff.)
It’s especially good for those attempting to breed fish, shrimp, or anything else. Infusoria grow abundantly on Java Moss — among the most effective ‘first foods’ for any aquatic organism.
Common Problems with Java Moss
I have brown or unhealthy sections of my java moss.
If the plant is thick, ensure that it’s not blocking light, or cutting off water flow to those areas of the plant. Water flow in the interior areas is critical to ensuring the plant stays attached and healthy.
If your Java Moss is new to your tank, it’s expected to have some dieoff/dieback occur as it acclimates to new water parameters. If your tank has warmer temperatures (above ~78º F/25ºC), Java Moss will grow at a reduced rate, and can struggle if it was previously in cooler water.
My Java Moss is thin, or not getting thicker.
“Slow growth conditions” (i.e. low/no light, low nutrients, low flow) will result in little to no new growth in Java Moss. If you’re able, try lowering your light to increase the light intensity that the moss receives. Check your water parameters to ensure you don’t have unexpected values, and that there are nutrients available for it to grow. (A bare tank with no fish — an extreme example — will result in almost any plant dying.) Also check the most common issue with Java Moss, below:
My Java Moss has algae growing on it.
In tanks with low (or no) water flow through/around the moss, algae will build up on the surface of the plant. When it’s left on there, it will slowly choke out the moss, blocking light and water. It’s best to maintain moss on a weekly basis, gently agitating its stems to prevent algae buildup. (Once algae is allowed to stay on Java Moss, it’s very, very challenging to separate it from the plant itself.)
How do I save my dying Java moss?
Typically, Java Moss only dies when it has extremely unfavorable growth conditions — it’s usually one of two causes: a change in available light, or it’s grown too thick to allow light/water flow into the interior of the plant.
You can solve both by ensuring enough light’s being provided (ensuring your light’s suitable for growing plants (i.e. it outputs PAR) or increasing the length of your light duration), and checking the flow of water in your tank. Flow is the main distribution method of nutrients around your tank, and since plants can’t move to where the nutrients are the flow has to be enough to bring the nutrients to them.)