Pearl Moss (Plagiomnium Affine): Ultimate Care Guide

Common Name(s)Pearl Moss
Scientific NamePlagiomnium affine
Ease of GrowingEasy
PlacementAttached to rock or wood
Temperature50 – 86 °F(10 – 30°C)
Growth RateVery Slow
PropagationSplit off daughter plants
Light RequirementLow to Medium
CO2 RequirementLow
Pearl Moss (Plagiomnium Affine)
Pearl Moss (Plagiomnium Affine). Edited. Salicyna, CC BY-SA 4.0

Pearl moss, otherwise known as plagiomnium affine, is an interesting moss that has round leaflets that form at the end of each frond.  Pearl moss is fairly rare, bright green moss that is quite compact and vertical growth habit.  It can be placed in the foreground or the mid-ground, however, it also works well on rocks, wood, or along the side of the tank.  This pearl moss is relatively new to the aquarium hobby trade and is rare because of its incredibly slow growth speed.  With a hardiness zone between five and eight, this fluffy bright green moss makes any aquarium pop as its bright green color shines in any setting.  The pearl moss is a leafy moss that forms upright shoots.  The pearl moss is also characterized by its signature round leaves that sprout from the main stem, which creates a beautiful grassy green look to the tank.  The plant can be emerged on moist surfaces and are fairly easy to set up once you get them into place. 

Taking care of the pearl moss is key to having them thrive in your tank.  By following guides on how to care for the pearl moss, you will raise your chances of keeping your pearl moss alive and well.  It is also good to plan your aquarium before buying anything.  You certainly want to group creatures and plants together that have similar environments to get the most variety, while keeping everything in the tank happy.

Pearl Moss Care

The aquatic moss known as pearl moss is relatively easy to care for assuming that you have taken the proper precautions and have set the environment to its necessary parameters.  Caring for pearl moss is similar to that of other aquatic moss species, except that the pearl moss does require a bit specific care.  Remember that pearl moss is an extremely slow grower and requires a lot of time and patience.  You will also need to think about where exact in your tank that you want to place the pearl moss.  Follow these tips to ensure that your pearl moss thrives inside your tank.

Lighting Requirement

The pearl moss needs low to medium light in order to thrive.  The quality light source cannot be too strong as it will dry out or damage the pearl moss.  Be sure to monitor how much light your tank is getting so that there is no disturbance to the pearl moss’s growth or health.  Any sort of low level lighting that you can find in a store should work efficiently. 


The pearl moss can survive in a wide range of temperatures.  Pearl moss can do well in temperatures ranging from 50 – 86 °F (10 – 30°C).  Anything colder than that will damage or kill off the pearl moss and anything warmer than that temperature will have a similar effect on the pearl moss as the light.  Therefore, it is important to keep monitoring your temperature and make sure that it stays in the ranges indicated.  For stronger possibility of growth, it would be good to try to aim for somewhere in the midrange for temperatures.  A temperature between 69-75°F should be a bit more ideal for the pearl moss to survive.  This way, this water temperature is not too cold or hot and leaves a bit of flexibility in the water. 

Pearl Moss pH

The pH level needs to stay between 5-8.  Anything lower or higher than this could cause damage to the pearl moss and stunt its growth or kill it altogether.

Pearl Moss Growth Rate

As mentioned before, the pearl moss grows very, very slowly.  The moss can grow in submerged or emersed conditions, but it will still grow at a slow rate.  If divided into pieces, the moss requires some time to settle, but will start to grow slowly.

As for the height, most pearl moss will not grow any higher than one or two inches high.  Moss is not known to grow very high, however if given the chance, it will grow alongside walls, rocks, and wood.  If you have any of these spaces available in your tank, you can put the pearl moss on top of it and it will settle there.

Pearl Moss Co2 Requirement

As mentioned before, this plant does really well in low light.  Furthermore, it does not need much CO2 to thrive.  A low CO2 injection and any kind of quality aquarium soil will yield better growth for the pearl moss.  The low dose and nutrients are fairly necessary as pearl moss tends to be susceptible to algae growth. 

Pearl Moss Propagation

In order to propagate pearl moss, you will need to start with cutting or pulling apart the moss.  It is a relatively simple process since all you have to do is break off pieces of the moss and place it where you want it to grow.  It might take some time for it to settle, but as long as you have the correct conditions, it will eventually grow.  You can actually create a carpet of pearl moss by buying a large bundle and using a grid system to carpet the bottom of the tank with the pearl moss.  After the pearl moss grows in each section, the entire bottom is a luscious green fuzz. 

There are also tissue culture plants that are grown in vitro in a laboratory that specializes in aquatic plants.  These institutions provide the best option for anyone that is looking to ensure that absolutely zero unwanted pests are introduced to their aquarium. 

Pearl Moss for Sale

If you are looking to buy some pearl moss for your aquarium, then there are a few options from where you can buy them from.  There are online stores like and Etsy that sell the pearl moss at a decent price.  Most pearl moss are generally under $15 and can be bought in bulk from most places.  Be sure to do some due diligence before you purchase anything to make sure you are getting good quality plants, which mean reading reviews and calling the store to ask relevant questions.

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