Alternanthera reineckii · also called AR, Scarlet temple, Alternanthera reineckii 'Rosanervig', Roseafolia
🐾 Pet-safe
Generally non-toxic to cats and dogs.
One of the most popular red/pink aquarium plants, with lance-shaped leaves that are green-to-olive on top and vivid pink-to-purple underneath. A striking color accent in planted layouts.
ℹ️
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Quick facts
Category
Aquatic Plants
Family
Amaranthaceae
Native origin
South America (Paraná river region of Argentina, Brazil, Paraguay)
Care difficulty
Intermediate
Light
Medium light
Pet toxicity
Pet-safe
Light
Medium to high light brings out its best coloration; roughly 30-60 PAR. Low light gives weaker, more olive tones and leggier growth, while high light produces intense pink, red, and purple leaves and compact form.
Water
Temperature 22-28 C (72-82 F), pH 5.5-7.5, soft to moderately hard water (GH 3-12). Responds strongly to a complete water-column fertilizer; iron and micronutrients are important for vivid red color. Good macro availability supports healthy leaf size.
Soil & potting
A rooted stem plant (not an epiphyte) that benefits greatly from a nutrient-rich substrate. Use aquasoil or add root tabs for the strongest growth and color. Plant stems individually into the substrate.
Environment — humidity, temperature, placement
CO2 is not strictly mandatory but is highly recommended — AR is notably easier, denser, and more colorful with pressurized CO2, and can struggle or melt without it in high light. Use as a midground accent or grouped background bush. Prefers gentle to moderate flow. Grows emersed and submersed; emersed (nursery) stems often melt and re-grow when first submerged.
Propagation
Propagate by topping and replanting the cut tops; the base produces multiple side shoots. Cuttings and lateral shoots root reliably, allowing you to build a dense red bush over time.
Toxicity detail
Non-toxic and safe with fish, shrimp, and snails. Native to South America; not considered an invasive of concern in the aquarium trade, but as always do not release aquatic plants into the wild.
Growth stages
How this plant changes through its life — each stage often has its own care, diet and space needs.
Photo coming soon
Spore / recruit
Aquatic plants and macroalgae establish from spores, seeds, or drifting fragments that settle and attach to substrate or rock. Many freshwater aquarium plants and marine macroalgae also spread readily from a detached piece that takes root or holdfast.
Photo coming soon
Young growth
Young growth puts out its first blades, fronds, or leaves and anchors with roots or a holdfast. Submersed plants may look different from their emersed form, and growth speeds up as the plant adapts to the water's light and nutrients.
Mature
A mature aquatic plant or macroalga reaches its full size and characteristic shape, forming the dense growth, runners, or fronds typical of the species. Established plants spread to fill space and can be divided or trimmed to propagate.
Varieties & cultivars
Natural forms are the wild species; cultivars are selectively-bred colour or variegation forms of the same plant.
Natural forms1
Reineckii (red)
The standard form with olive-green tops and rich pink-to-magenta undersides, a popular splash of colour among green plants.
💡 High light, CO2 and iron deepen the pink-red; in low light it loses colour and grows leggy.
Cultivars2
Rosanervig / Rosaefolia
Selection with striking pale pink-and-white veins standing out against pink-red leaves. Highly ornamental.
💡 Needs bright light and good nutrients to show the contrasting veins; otherwise care matches the standard form.
Mini
Compact, low-growing cultivar with small reddish-pink leaves, used as a colourful carpet or foreground rather than a stem plant.
💡 High light keeps it low, dense and red; in dim light it stretches upward and pales.
