Alternanthera Reineckii, also known as “Scarlet Temple”, “Reineckia” or “Ruby Red,” is a stunning aquatic plant that can add color and texture to any freshwater tank. This amazing plant is prized for its distinctive red foliage, which grows in dense clusters along the stem.
It’s worth noting right from the begining that while many sources refer to this plant as easy and low-maintenance, this is not entirely true.
Alternanthera reineckii requires bright lighting, CO2, and good fertilization in order to thrive and maintain its vibrant red color.
If these conditions are not met, this plant may still grow (this is true) but its leaves will become lackluster and lose their coloration. As such, I would not recommend this plant for beginners or those looking to use it in low-tech tanks.
In this article, I will explore the care requirements of Alternanthera reineckii, as well as tips for successfully propagating and displaying this beautiful aquatic plant in our tanks.
Quick Notes about Alternanthera Reineckii
|Common Name||Alternanthera Reineckii|
|Other Names||Scarlet Temple, Reineckia, Ruby Red, Water hedge, or AR|
|Lighting||Moderate to high|
|Optimal pH||6.0 – 7.0|
|Optimal GH||2 – 12|
|Optimal Temperature||71 – 82°F (22 – 28°C)|
|Can Be Grown Emersed
|Growth Rate||low ro moderate|
|Placement in Tank
||midground and background
(‘mini’ version – foreground)
|Aquarium size||2 – 12 inches (5 – 30 cm)|
||Red, purple, and pink|
Interesting fact: Alternanthera Reineckii has medical properties. In the community, this plant is used to treat digestive problems and diarrhea.
Etymology of Alternanthera Reineckii
The genus name Alternanthera comes from the Latin words “Alternans”, meaning “Alternating”, and “Anthera”, meaning “Anther”, in reference to the alternate barren anthers found in this genus.
John Isaac Briquet named this species after German botanist Eduard Martin Reineck (1869 – 1931).
Distribution of Alternanthera Reineckii
Alternanthera reineckii is a freshwater ornamental plant that can be found in South America.
This species is native to Bolivia (Santa Cruz), Argentina (Buenos Aires, Chaco, Corrientes, Entre Rios, Formosa, Misiones, Salta, Santa Fe), south Brazil (Parana, Rio Grande do Sul, Santa Catarina), Paraguay (Cordillera), Uruguay (Artigas, Paysandu, Rivera, Salto, Treinta y Tres).
In South America, Alternanthera reineckii is generally known as “Pequeña Hoja” plant (small leaves).
Habitat of Alternanthera Reineckii
Alternanthera reineckii occurs in two forms semi-terrestrial and aquatic. It is abundant in and a little out of very shallow waters of swaps, ponds, bogs, lakes, and slow-moving streams.
Water and waterlogged conditions are well known to be associated with the presence of this species.
Description of Alternanthera Reineckii
- Growth form. Alternanthera reineckii can be grown emersed (in paludarium) or submersed (in aquariums).
- Stem: Its pubescent stem can be between 2 – 12 inches (5 – 30 cm) in height.
- Leaves size: Depending on its morph type, this plant can have elongated and wide leaves from 1 to 3 inches (3 – 8 cm) long. Its leaves can either be attached directly to the stem or have a short petiole, are arranged in pairs. The neighboring pairs of leaves are arranged perpendicularly to each other.
- Color: The color of the leaves typically varies from shades of red and pink to yellow, depending on the plant’s form.
- Flowers: This is a flowering plant when grown emersed. The inflorescence is axial and appears in clusters of 1 to 5 spikes, each filled with many densely arranged flowers. The flowers are usually white, or blue-pink and ovoid in shape.
- Roots: The roots are weak in the beginning but become massive when the plant settles.
Alternanthera Reineckii Variation
The number of variations of Alternanthera reineckii is not certain.
For example, Christel Kasselmann (an internationally recognized expert on aquarium plants) describes five forms of this plant in her books, among which Alternanthera reineckii ‘roseafolia’ (also known as Alternanthera reineckii ‘Pink’) is the easiest to cultivate and the most commonly found in the trade.
Nevertheless, in the trade, there are more, such as:
|‘Mini’||crimson, bright red, purple, and pink||2 – 4 inches (5 – 10 cm)|
|Rosanervig||Mostly pink with lightly colored veins.||6 – 12 inches (15 – 30 cm)|
|Rosaefolia||Reddish to olive coloration||6 – 8 inches (15 – 20 cm)|
|Lilacina||Brownish-green (copper-like) with hues of pink to red color.||3 – 6 inches (7 – 15 cm)|
|Cardinalis||Dark red||6 – 12 inches (15 – 30 cm)|
|Ocipus||Yellowish-green with a pink underside||6 – 12 inches (15 – 30 cm)|
|Variegated||Purple-red||6 – 12 inches (15 – 30 cm)|
Note: Keep in mind that all these ‘forms’ are not actual subspecies of Alternanthera reineckii. They are merely trade names used to identify aquarium plants that do not have any recognized botanical classification. In other words, they are basically the same plant with minor differences.
Tank Requirements and Water Parameters
In order for this plant to show itself in all its beauty, certain requirements must be met.
The optimal tank size for this plant will depend on the variation you have chosen.
For example, Alternanthera reineckii ‘mini’ can be kept in a small nano tank, while other variations of this plant will require significantly more space and a minimum recommendation of 10 gallons (40 liters).
Water type, Temperature, Hardness, and pH:
Temperature: This plant is not tolerant of very low temperatures and is sensitive to temperature fluctuations. The ideal water temperature range for the plant is 71 – 82°F (22 – 28°C).
If the temperature drops below 68°F (20°C), the growth significantly slows down. At the same time, a temperature above 28°C can cause changes in the shape of the leaves.
pH: Alternanthera reineckii prefers slightly acidic water with a pH between 6.0 and 7.0. In alkaline water, the leaves age and deteriorate quickly.
Hardness: It can grow in moderate to hard water (from 6 to 12 GH). In very hard water it often melts.
Alternanthera reineckii requires powerful illumination (>40 PAR). Strong light gives this plant a decorative red color.
Although the plant can tolerate moderate lighting, eventually, it will have its consequences. After some time, it will lose its bright color when kept in conditions of insufficient lighting.
Thus, if your light is really low, you will not have any success with this plant.
The duration of photoperiod needs to be selected individually so that, on the one hand, Alternanthera reineckii has enough light, and on the other hand, not to cause an outbreak of algae. Usually, 8-10 hours a day is sufficient.
Alternanthera reineckii is a relatively versatile plant. Despite having a powerful root system, can also obtain nutrients from the water column.
Even though some aquarists plant and propagate this plant in sand and even gravel substrates, I still tend to believe that this plant requires nutrient-rich substrates, period.
|The reason is that (in my experience as well), it has been observed that if Alternanthera reineckii is planted in inert substrates, it will grow a crazy amount of aerial roots. In addition, its growth rate is absolutely inconsistent. It is like the plant is desperately trying to find additional sources of nutrition.
At the same time, when planting this plant in nutrient-rich soil, the situation changes fundamentally. That is why using nutrient-rich substrate is more preferable for this plant.
CO2 and Fertilization:
CO2: The use of CO2 for this plant is a highly debated topic, with some aquarium enthusiasts successfully growing Alternanthera reineckii even without it.
However, in most cases, using CO2 results in a significant improvement in the plant’s quality, including faster growth, a desirable red hue, and a more lush appearance, rather than just a single stem growing upward. All in all, Alternanthera reineckii loves high CO2 levels.
Without CO2 the coloration and speed of growth will be …just really bad and slow.
Fertilizer: Alternanthera reineckii also requires periodical supplementation. If there is a lack of micronutrients, this plant will be affected and the leaves will turn pale in color. The basic necessary chemical elements are: Nitrogen (N), Phosphorus (P), Potassium (K), and Iron (Fe).
At the same time, this plant also does not tolerate too much of either micro or macro elements in the water (for example, nitrates should be <5 ppm). Overdosing with fertilizers can cause plants to stop growing, at best.
In my opinion, adding liquid fertilizers would be more optimal than using root tabs.
Important: If you keep shrimp in the tank with the Alternanthera reineckii, I would highly recommend reading my articles:
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 Alternanthera Reineckii
Alternanthera reineckii is a challenging plant to care for and requires specific conditions for optimal growth and visual appeal. That is why this plant, in my opinion, is not recommended for beginners because it requires excellent attention to its initial pruning and regulation of light, CO2, and nutrients.
To keep this plant healthy and red:
- Do regular water changes. The water change should be 30-40% Otherwise, the plant may cease its growth.
- Control your water parameters. Any changes should be slow and gradual.
- Provide lots of light lighting with a higher red/blue spectrum and implement an effective fertilization
Do not expect this plant to grow right from the start. Alternanthera reineckii does not grow until its roots have adjusted to the new surroundings, and this adjustment period can take a while. To minimize the impact on the plant’s growth, it is advisable to limit its movement as much as possible.
Under suboptimal conditions, submerged growth is very slow.
However, if a plant receives all the necessary resources, its growth rate will increase significantly, reaching a moderate level.
Carry out formation pruning by cutting secondary lateral branches or leaves in the case where elongated growth is desired.
I would also say that you should not let Alternanthera reineckii’s shoots grow above the water level in the tank. If the plant reaches the surface, it will shed its underwater leaves and leave a bare stem underwater.
To prevent this, it is crucial to regularly trim the plant’s top and prevent it from transitioning to an aerial environment. The trimmed stem can be used for replanting.
Planting Alternanthera Reineckii
Alternanthera reineckii is a plant with long stems (except its ‘mini’ version) and is generally planted along the sides of an aquarium, in the midground, or background.
Also, do not plant the stems too close to each other (keep them 2 inches (5 cm) apart). In cramped conditions, this plant often drops its leaves.
You can use a pair of tweezers (link to check the price on Amazon) to gently place the stems into the substrate to avoid damage.
Propagation of Alternanthera Reineckii
Alternanthera reineckii is very easy to propagate. This plant can be propagated in two ways:
- by side stems and
- through cuttings
Side stems. As soon as this plant has lateral shoots (with its own root system), it will be enough to separate the mother stem from the daughter stem (lateral shoots).
Note: One of the main drawbacks of this method is that by this moment the plant’s root system may already be very developed. Therefore, it may be very problematic to pull out the mother plant in order to divide it later.
- Take the stem and cut it from the top side (it should have at least 4 leaves on the stem).
- Insert a new stem into the substrate to root.
As the plant grows, you will see that some aerial roots will start to form from the nodes along the stem. Cut a piece of the plant with these roots and plant it in the soil. Even if the cut plant doesn’t have roots yet, you can let it float in water. In a few days, you will see the growth of such roots.
Alternanthera Reineckii and Dry Start Method
The Dry Start Method is a technique for cultivating Alternanthera reineckii in which the plant is grown without any water initially. This will allow for an increased concentration of carbon dioxide in the tank and will not require the purchase of any additional equipment.
- Instead of immediately filling the tank with water after planting, we only need to add enough water to reach the surface of the lowest part of our substrate.
- Next, use tweezers to plant Alternanthera reineckii and sprinkle them on top of a substrate.
- Cover the top of the tank with cling wrap to increase the humidity.
- In about 5 or 8 weeks you can flood the tank.
Problems Associated With Alternanthera Reineckii
Not very resilient: Alternanthera reineckii cannot absorb heavy metal (water pollutants) in the water without taking damage. According to the study, the lowest viability level is observed for Alternanthera reineckii, which only reached 26.67% survivability.
For example, Bacopa sp. has shown the ability to absorb large amounts of heavy metal elements with a 100% survival rate.
Solution: Check your water quality. Use RO systems if needed.
Color loss (Chlorosis): When the plant shows color changes, for example, it becomes yellowish and/or pale, it indicates a lack of lighting, CO2, and/or deficiency of nutrients, mainly nitrogen and iron (Fe).
Solution: Improve lighting and filter the water, apply NPK.
Rotting (Necrosis): Sometimes on the leaves of this plant we can see holes or spots of decay. This is usually a result of a lack of micronutrients, light, and less often – a change in pH.
Solution: it is recommended to eliminate withered leaves and prune for sanitation, leaving only healthy stems of green color and healthy leaves, improve lighting and filter the water, apply NPK.
Melting: A transition from emersed form to submersed form may trigger a melt of the green foliage, however, Alternanthera reineckii will recover from this state when it settles fully in the tank.
Solution: Be patient. Wait and the plant will bounce back.
Algae: Alternanthera reineckii is susceptible to algal growth, especially if the light is excessive and nutrients are plentiful.
Solution: Algae can be curbed by making some adjustments to the lighting intensity, regular water changes, and the introduction of algae-eaters into the tank.
Relocation: Alternanthera reineckii does not like to be moved. If you plan to relocate or remove this plant, be cautious as its massive root system can even damage the stem. Take it out gradually to avoid pulling up too much substrate.
Solution: There is no alternative solution, just proceed with care.
Aerial roots: Alternanthera reineckii has lots and lots of aerial root, especially in the lower part of the plant. To be honest, they look really ugly.
Solution: You can trim them off (if you have patience) so the plat will look like in beautiful pictures (Yes, people generally trim these roots before taking pictures!). Another option is to plant the plant behind other plants so you will not see them on the lower part.
Keep in mind that the growth of aerial roots usually occurs in 3 scenarios:
- It is planted in an inert substrate (sand, gravel, etc.).
- When the plant is in a shady area and does not receive adequate light, particularly for its lower nodes.
- When the stems begin to grow horizontally instead of vertically.
However, if you maintain proper lighting and keep the plant upright, it should not pose a significant issue.
- How to Spot Nutrient Deficiencies in Aquatic Plants
- Everything about Nitrates in Planted Tanks
- Phosphates in Freshwater Tanks
Benefits of Alternanthera Reineckii
Aquascape: When it comes to aquascaping, Althernanthera reineckii is an excellent choice for adding a focal point and decorative touch to the jungle or Dutch style aquascapes due to its unique color and form.
Oxygenation: Helps to generate oxygen in the tank water. Althernanthera reineckii has a distinct feature which is the production of small pearls or bubbles of oxygen that stays on top of the plant, this adds a very lively aspect to the plant.
Hiding place: This plant also serves as an important hiding place and source of shade for small fish and invertebrates, thanks to its tunnel-like structure which can provide refuge from predators and serve as a nursery area.
Foraging place: Acts as a buffet of biofilm, which is an ideal first food for newly hatched fry and shrimplets
Prevents gas pockets: This plant has a well-developed root system that will help to break up anaerobic pockets in the substrate.
Note: Hydrogen sulfide pockets (H2S, the gas smells like rotten eggs) can be really dangerous to your fish or shrimp.
Alternanthera Reineckii and Compatible Tankmates
Personally, I have never had this problem, but I know that some aquarists have complained that Amano shrimp have eaten their Althernanthera reineckii.
In reality, I suspect that the Amano shrimp were not to blame.
These shrimp are voracious algae eaters. Thus, I believe they did what they have to – they were eating the algae growing on the plants. The fact that the leaves of these plants were damaged was most likely the result of the algae and/or nutrient deficiency in the plant.
Avoid or Be Careful
Avoid fish species that may damage the plant or find Althernanthera reineckii too delicious, such as Silver dollars, Buenos Aires tetras, Koi fish, Goldfish, Oscars, Rainbows, Jack Dempsey, Clown loaches, and African Cichlids. These species can cause problems in the planted tanks.
Additionally, Althernanthera reineckii and most types of crayfish or freshwater crabs are not compatible, as they may cut, eat, and uproot everything in the tank. It’s important to research and consider these factors before setting up your aquarium.
Quarantine Alternanthera Reineckii
If you are unsure of the source or quality of the plants, quarantining Althernanthera reinecki will allow you to ensure that the plants are healthy and free of any potential threats before being added to your tank.
- The plant can have parasites, and hitchhikers like pest snails, or even predators (dragonfly, damsefly nymphs, etc.).
- It could also be treated with chemicals (pesticide) to remove parasites, snails, etc. However, these chemicals are extremely poisonous to fish, shrimp, and other invertebrates.
According to the study, a 10% solution of hydrogen peroxide (for 1-2 min) is a great way to do so.
To find out more, read my articles:
- How to Remove Snails from a Shrimp Tank.
- How to Quarantine and Disinfect Aquarium Plants.
- Pesticides in Shrimp Tanks. Plants Quarantine.
Alternanthera reineckii is one of the most attractive plants to add to the water landscape. Its vibrant red color with the right conditions and small size makes it a popular choice among aquarium enthusiasts.
The main downside though is that this is not a low-maintenance plant. This is a very demanding plant.
Alternanthera reineckii requires strong lighting, CO2, and regular fertilization. Therefore, be ready to provide it for this plant.
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- Mears, J.A., 1977. The nomenclature and Type collections of the widespread taxa of Alternanthera (Amaranthaceae). Proceedings of the Academy of Natural Sciences of Philadelphia 129.
- Niemann, Hendrik J. A preliminary assessment of the role of aquarium trade in the spread of non-native aquatic plants in South Africa: a DNA barcoding approach. University of Johannesburg (South Africa), 2019.