The Com­plete Care Guide to Java Moss

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. (18 – 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! (Just a note here that if you have oth­er plants that do require rel­a­tive­ly-hot­ter tem­per­a­tures, Java Moss will be per­fect­ly fine at high­er tem­per­a­tures, it just won’t grow quite as quickly.)

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. Of course, all plants need light of some sort, so 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.

A note on flow

Java Moss has a ten­den­cy to get so dense that it can block the flow of water through inte­ri­or por­tions of the plant. Since plants can’t move to reach nutri­ents, a lack of flow reduces (or elim­i­nates) the sup­ply of nutri­ents, and that por­tion of the plant can eas­i­ly die. It’s crit­i­cal the you peri­od­i­cal­ly trim the plant to ensure it does­n’t get overly-bushy.

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.

Prop­a­ga­tion

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!) If you’re going for that nat­ur­al look, it’ll even sur­vive being put through a light cycle in a blender to cut it into fine, small pieces. This ​‘paste’ of Java Moss can be glued or oth­er­wise-bound to hard­scape for a very fast nat­u­ral­ly-grow­ing look.

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.

Com­pat­i­bil­i­ty

This plant has no con­flicts — it’s great for shrimp tanks, fish tanks, and every­thing in between. (Fry love this stuff.) Remem­ber, though it grows fastest at cool­er tem­per­a­tures, it’s also able to sur­vive in a wide range. That means it’s com­pat­i­ble with most-any oth­er flo­ra or fau­na species in fresh­wa­ter tanks.

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 the thick out­er por­tions aren’t block­ing light or cut­ting off water flow to inte­ri­or areas of the plant. Water flow through the entire plant mass is crit­i­cal to ensur­ing the plant stays attached and healthy.

If your Java Moss is new to your tank, it’s expect­ed to have a por­tion of it ​“die back” as it accli­mates to new water para­me­ters. (Though this isn’t required—prop­er hus­bandry can pre­vent this dieback period.) 

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?

Blunt­ly: Java Moss is actu­al­ly real­ly hard to out­right kill. Typ­i­cal­ly, Java Moss only dies when it has extreme­ly unfa­vor­able growth con­di­tions — it’s usu­al­ly one of two caus­es: a dras­tic change in avail­able light (i.e. com­plete dark­ness or close to it), or it’s grown too thick to allow light/​water flow into the inte­ri­or of the plant.

You can solve both by doing a few things:

1: Ensur­ing enough light is being pro­vid­ed, and that the light is suit­able for grow­ing plants. That means it out­puts PAR, not just light for humans like lumens or lux. You might also con­sid­er increas­ing the pho­tope­ri­od slight­ly and increas­ing the strength of your light source.

2: Ensur­ing that water flow is strong enough around and through the java moss. 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.