Red Moss Care Guide – Planting, Growing, and Propagation

Caloglossa Beccarii (Red moss) Care Guide – Planting, Growing, and Propagation

Caloglossa beccarii is an exceptionally beautiful red algae that aquarium enthusiasts begin to use as a decorative plant. Due to its resemblance to moss, it is often referred to as Red moss.

Being algae by nature, Red moss is quite hardy and adaptable to various water parameters. This makes it relatively easy to maintain even for beginner aquarists. At the same time, like any other algae, Caloglossa beccarii can also be challenging to control, especially in large tanks.

Therefore, if you are considering buying it, in this article, I have tried to describe everything known about Caloglossa beccarii, including care, maintenance, propagation, common issues, and more.

Quick Notes about Caloglossa Beccarii

Common Name Red moss
Other Names Flat-bladed red algae or Mangrove Red algae
Scientific Name
Caloglossa beccarii
Difficulty Easy
Lighting Low to high
pH 5.0 – 8.0
GH 1 – 20
Temperature 64 – 84°F (18 – 29°C)
Substrate Any 
Can Be Grown Emersed
Growth Rate Slow – moderate
Placement in Tank
Aquarium size 2– 4 inches (5 – 10 cm)
Low requirements
CO2 Not needed
Propagation Vegetatively
Brown to violet, or reddish

Interesting fact: This alga is utilized as a food in Thailand since it is rich in minerals (calcium, potassium, manganese, iron, and magnesium), carbohydrates, and protein. It also has a high level of vitamin C and linolenic acid.

Taxonomy of Caloglossa Beccarii     

The genus Caloglossa is widespread in tropical to temperate mangrove, estuarine, and freshwater habitats. Currently, there are 22 accepted species within this genus. However, only 6 species have been documented in freshwater streams to date.

Kingdom: Plantae (plant)
Phylum: Rhodophyta (red algae)
Class: Florideophyceae (multicellular red algae)
Order: Ceramiales (Complex thallus)
Family: Delesseriaceae 
Genus: Caloglossa
Species: Caloglossa beccarii

Distribution of Caloglossa Beccarii   

Caloglossa Beccarii (Red moss) Care Guide – Planting, Growing, and Propagation DistributionThe alga has been documented in various locations, including India, Northern Australia, Malaysia, Singapore, Thailand, and Vietnam.
Note: A single report of Caloglossa beccarii from Panama has been questioned, and scientists are inclined to believe it may indeed be a different species.

Habitat of Caloglossa Beccarii 

Red moss is typically found attached to barks of mangrove plants and rocks in freshwater shallow streams and rivers. It usually forms patches in areas with moderate water flow and high turbidity.

Description of Caloglossa Beccarii    

Caloglossa Beccarii (Red moss) Care Guide – Planting, Growing, and Propagation profileStructure. This alga has leafy, lanceolate, or flat structures. It feels very pleasant to the touch.

Leaf. It branches in a forked pattern, and each leaf is slightly pinched in the middle. There’s a noticeable line running down the middle of each leaf. Caloglossa beccarii usually has 4 to 5 rows of cells along its main axis. The flat blades have clear sections between them.

Size. It generally grow in the range between 2 – 5 inches (5 – 10 cm) long.

Coloration. It can range from dark brown to violet, or reddish.

Roots. Caloglossa beccarii has tiny roots (rhizoids) that stick out from the bottom, but they don’t join together.

For a more detailed and scientific description of Red moss, you can read in this study.

Note: Systematic studies were conducted on Red algae species Caloglossa, including C. beccarii, C. fluviatilis, C. ogasawaraensis, and C. stipitata, to identify morphological differences. Species identification focuses on branching patterns, rhizoidal position, node constriction, midrib, wing cells, apical cell, row number, midrib, etc.

To be honest, without proper knowledge and equipment, it’s practically impossible for the average aquarium enthusiast to see the differences.

Tank Requirements and Water Parameters

Caloglossa beccarii is stunningly beautiful and remarkably easy to care for. However, once established, it can be really hard to get rid of, so keep this in mind.

Tank size:

The size of the tank doesn’t matter much. This plant will thrive anywhere.

Important: However, from a practical standpoint, I would NOT put this plant in large tanks, for example, over 10 gallons (40 liters). Mostly because when it grows and reproduces, it will spread everywhere. So, if you ever decide to remove it from the tank, it could become a real problem!

Water type, Temperature, Hardness, and pH:

Caloglossa Beccarii (Red moss) Care Guide – Planting, Growing, and PropagationTemperature: Caloglossa beccarii does best in warm tropical temperatures from 7584°F (24 – 29°C). At the same time, experiments with it have shown that it also thrives well within the range of 64 – 71°F (18 – 22°C).

pH: It can grow within a pH range of 6 to 8. This is indeed true, as the Red moss is highly resilient and not demanding of conditions. However, the optimal pH range varies from 7 to 8. At the same time, it has been observed that at very high pH levels, it starts losing its reddish hue and becomes paler.

Hardness: This alga grows better and faster in hard water (GH 8 – 20). In soft water, it will just grow slower.

Salinity: This is a freshwater algae, and can still tolerate only low salinity (<5pmm).


Red moss will thrive both in low-light aquariums and in bright light.

However, optimal growth is observed under full-spectrum lighting. I would repeat that the spectrum of light is more critical here.

Related articles:


In nature, Caloglossa beccarii grows in streams and rivers.

Although it is not mandatory but a gentle water current would be optimal for Red moss. It will help to distribute nutrients and oxygen throughout the plant, promoting healthy growth.


No special requirements.

Caloglossa beccarii needs driftwood and rocks, as they serve as the primary attachment points.

Note: Driftwood is preferable as it provides easier anchorage for the plant, allowing it to grow more vigorously, bushy, and rapidly.

CO2 and fertilization:

CO2: Not needed.

Fertilization: Macro and micronutrients will help to sustain healthy growth and ensure that the Red moss maintains the best coloration. Therefore, it is recommended to regular dose of liquid plant fertilizers (2-3 times a week).

Note: If you keep shrimp in the tank with Caloglossa beccarii, I would highly recommend reading my articles:
CO2 in a Planted Tank Guide
CO2 in a Shrimp Tank

How Copper Affects Dwarf Shrimp
Shrimp Safe Plant Fertilizers
The point is that a high level of CO2 and Copper (most fertilizers contain copper) is extremely dangerous to the shrimp.

Care and Maintenance of Caloglossa Beccarii  

  • This is a beginner-friendly plant.
  • Under optimal conditions, it typically exhibits a moderate growth rate, although it generally tends to grow slowly.
  • Since it does not grow tall, you will not have to trim it, if you do not want to.
  • This plant tolerates shadingvery well. Therefore, there is no need to worry about it.

Planting Caloglossa Beccarii    

Caloglossa beccarii is small and ideal for the foreground.

DO NOT plant it into the substrate! Instead, attach it to a piece of driftwood or rock. As it grows, the Red moss firmly adheres to these surfaces, often taking on the form of clusters or balls.

Similar to regular moss, it can also be shaped to create interesting aquascape designs in the aquarium, such as creating a carpet, tree, or cave overhangs. The principle is almost the same. You can read about it in my article on Java mosses here.

Propagation of Caloglossa Beccarii  

Red moss reproduces through its blades.

The reproduction of these algae involves three phases: male plants release spermatia to female ones, fertilizing the female gamete. The plant undergoes several divisions, forming a protected multicellular “embryo.” Upon maturity, it produces spores (blades) that germinate into new plants.

Fallen blades not only attach to driftwood and rocks but also to nearby plant leaves.

Problems Associated With Growing Caloglossa Beccarii   

Hard to control the form. Caloglossa beccarii tends to attach with one stalk and branch out. Without sufficient airflow, these stalks die off. So, when it grows in too large volumes, the bottom layer starts to die, and the entire cluster falls apart.

Solution: provide enough airflow and divide it periodically.

Hard to attach for the first time. I tried attaching it to driftwood, but large pieces may start decaying inside. Using a fishing line to secure the Red moss, as we usually do with other mosses, doesn’t work here because the area where the line is tied often simply rots.

 Solution: None

Hard to keep it in place. Once established in the tank, it tends to grow everywhere, especially, on plants.

Solution: None

Light competition (suffocates plants). This problem is directly related to the one described above. When the Red moss starts growing on other plants, they don’t receive the necessary light for photosynthesis and gradually begin to suffer and die.

Solution: You can treat the affected leaf with an algicide or manually clean the leaves, which can be a very time-consuming and tedious process.

Likes compact planting. When done in small/thin clumps, it takes a long time to spread.

Solution: None

Trimming. Trimming leads to bald spots, and it takes too long to restore its shape. Trimming might damage the lower attachments too.

Solution: None

Algae. It may sound strange, but other types of algae can outcompete Red algae. It usually gets covered in other types of algae in bright light, especially near the water’s surface.

Pale appearance. The loss of color in this plant mainly occurs due to poor light spectrum or excessively alkaline water.

Solution: Provide full spectrum of lighting/ Check your water parameters.

Sensitive to Seachem Flourish Excel. Like many types of algae, it does not like Excel.

In my opinion, it is quite obvious that Caloglossa beccarii is NOT suitable for all aquariums.

Personally, I would never recommend using it in large tanks with dense vegetation.

Initially, you may enjoy its attractive appearance, but over time, it can become a nightmare as it grows where it shouldn’t, interfering with other plants and ruining the overall look.

Benefits of Caloglossa Beccarii

Aquascape: In aquariums, Caloglossa beccarii can be used to create amazing aquascapes.

Foraging place: The structure of the plan acts like a buffet of biofilm, it also catches all the free-floating particles. Therefore, it creates a natural feeding ground for the shrimp. They will be constantly grazing on it.

Caloglossa Beccarii   and Suitable Tankmates

When planting this algae in the aquarium, there are some points to consider. Caloglossa serves as a treat for certain aquarium fish, such as cichlids.

In all other cases, it can be kept with dwarf shrimp, frogs, etc.

In Conclusion

Caloglossa beccarii emerged in aquarium collections relatively recently, in 1990. For its unique beauty, this rather rare algae has even been used by professional aquascapers.

However, due to limited information about it, aquarium enthusiasts who wish to purchase it may make a big mistake. While it is decorative, it is still an algae!

Unlike Marimo moss balls (Aegagropila Linnaei), which grow incredibly slowly, this alga can be invasive, and keeping it in the aquarium can have negative consequences, as I mentioned in the article.


  1. Kamiya, Mitsunobu, John A. West, Ulf Karsten, and E. K. Ganesan. “Molecular and morphological delineation of Caloglossa beccarii and related species (Delesseriaceae, Rhodophyta).” Phycologia55, no. 6 (2016): 640-649.
  2. West, John A., Mitsunobu Kamiya, E. K. Ganesan, Susan Louiseaux-de Goer, and L. Jose. “Caloglossa beccarii (Delesseriaceae, Rhodophyta) from freshwater rivers in Kerala, India, a critical new record.” Algae30, no. 3 (2015): 207-216.
  3. Latt, Cho Cho, and U. Soe-Htun. “The diversity and distribution of the genus Caloglossa J. Agardh (Ceramiales, Rhodophyta) in Setse and Kyaikkhami coastal areas.” Mawlamyine University Research Journal5 (2014): 1-22.
  4. Chankaew, W., D. Amornlerdpison, and N. Lailerd. “Characteristics of red macroalgae, Caloglossa beccarii DeToni from freshwater for food as safe and other applications in Thailand.” (2021): 1-12.
  5. Taxonomy and ecology of freshwater algae. Department of Botany St.Albert’s College. February 2014
  6. Sato, H. & Akiyama, H. 2002. Caloglossa beccarii (Ceramiales, Rhodophyta) from Thailand on the Malay Peninsula and its distribution in Southeast Asia. Nat. Hum. Act. 6:101-104.
  7. Sheath, R. G. 1984. The biology of freshwater red algae. Prog. Phycol. Res. 3:89-157

2 thoughts on “Red Moss Care Guide – Planting, Growing, and Propagation

  1. “The article sounds intriguing and fascinating.
    And actually it seems like a really successful thing, both an easy plant to grow and also beautiful.”
    “So is it basically like a kind of algae, just like the green algae that everyone hates, but red in color?
    I’d also love to know how I can buy this stuff?
    I’m trying to get a base going, but nowhere sells it. Everywhere I ask for something like that, they laugh at me because they’re fighting algae.”

    1. Hi YAKOV,
      That’s indeed a quite beautiful algae, but it’s not commonly sold in stores. You need to monitor online shops; that way, you’ll have a better chance of finding it.
      As for the sellers who laughed, on one hand, yes – it’s algae, and under certain conditions, it can also become a problem in the aquarium, which I deliberately pointed out. On the other hand, this algae can also serve as an ornament for the aquarium, unlike other types.
      Best regards,

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