Care at a glance
Easier than HC 'Cuba' with similarly tiny round leaves. Plant in tiny clumps 2–3 cm apart for fastest carpet. Pearls heavily under CO₂.
By Mike ElmiraUpdated 1 min read
Part of our complete guide to the planted aquarium.
PlantCarpet
Monte Carlo
Micranthemum tweediei
ArgentinaIntermediate
TL;DR, Monte Carlo
Easier than HC 'Cuba' with similarly tiny round leaves. Plant in tiny clumps 2–3 cm apart for fastest carpet. Pearls heavily under CO₂.
Monte Carlo (Micranthemum tweediei) is a carpet / stem aquatic plant for the foreground of a planted tank. It reaches 3–5 cm under good conditions and grows at a medium rate. Light: medium to high. CO₂: recommended. Target 20–26 °C, pH 6.0–7.5, and 1–10 dGH. Substrate: Fine, nutrient-rich substrate. Propagate via cuttings spread horizontally.
- LightMedium to High
- CO₂Recommended
Tank fit
The parameters that decide whether monte carlo fits in your tank.
Parameters
15 °C20 °C25 °C30 °C
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0 dGH5 dGH10 dGH15 dGH20 dGH25 dGH
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Low
Medium
High
None
Optional
Recommended
Required
Slow
Medium
Fast
V. fast
Still
Low
Medium
High
V. high
Profile
Family
Linderniaceae
Type
Carpet / Stem
Position
Foreground
Substrate
Fine, nutrient-rich substrate
Propagation
Cuttings spread horizontally
Habitat
Boggy clearings and stream banks of Argentina
Argentina
Who it lives with
Tank-mate safety and the species this one is documented to thrive (or fail) alongside.
Pro tips
Hard-won lessons from the tank.
Plant in 1-cm clumps spaced 2 cm apart on damp substrate before filling the tank — 'dry start method' (DSM). DSM gets you a complete carpet in 3–4 weeks before water ever enters the tank. Pearling under CO₂ is one of the most rewarding aquascaping sights.
Things to watch for
What can go wrong and how to spot it.
Things to watch for
Failure modes, in order of how dramatic the fix is.
Nutrition
Common deficiencies
Stretchy growth (leggy stems): insufficient light. Pale: nitrogen. Yellowing: iron.
Algae
Algae issues
Hair algae attaches easily to dense growth. Stable CO₂ and proper light cycle prevent this.
How to care for it
The practical routine, read top to bottom.
Fertilization
Moderate root feeder. Root tabs help; column macro and CO₂ are important for compact dense growth.
Trimming
Trim with sharp scissors every 3–4 weeks once established. Trimming forces horizontal spreading.
Background
Where it comes from, how it behaves, and the variants you'll see at retail.
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In the wild
Where it lived before it came home.
Native rangeArgentina
Origin · Argentina
Wet streambanks and pond edges in Argentina; usually grows emersed.
Emersed form
Almost all retail Monte Carlo is emersed-grown — leaves are slightly larger and firmer. Transitions easily to submerged form.
Flowering
Tiny white flowers emersed; never flowers submerged.
Variants & identification
The named cultivars and the lookalikes worth flagging.
Variants / cultivars
Only one form sold under this name. Sometimes confused with Hemianthus callitrichoides ('HC Cuba') which has smaller, rounder leaves.
Misidentification
Often confused with HC Cuba — Monte Carlo has slightly larger leaves and is significantly easier. Pearlweed (Hemianthus micranthemoides) is the third commonly confused species.
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
Does Monte Carlo need CO₂?
CO₂ requirement: recommended. Light requirement: medium to high. Under low-tech conditions the plant grows at a medium rate.
What light level does Monte Carlo need?
Monte Carlo (Micranthemum tweediei) needs medium to high light. Run a photoperiod of 6–8 hours; longer photoperiods invite algae unless CO₂ and dosing are dialled in.
Where should Monte Carlo be planted?
Position: foreground. Substrate: Fine, nutrient-rich substrate It typically reaches 3–5 cm.
How do you propagate Monte Carlo?
Propagation method: Cuttings spread horizontally. Monte Carlo is a carpet / stem plant.
What water parameters does Monte Carlo tolerate?
Target 20–26 °C, pH 6.0–7.5, and 1–10 dGH. Flow tolerance: low to medium.
Is Monte Carlo suitable for beginners?
Difficulty: 3/5. Intermediate, stable parameters and a mature tank matter.
Sources & further reading
More plants
See all plantsAdjacent specimens in the catalogue.
Cross-references
Build the rest of the tank.
A planted tank is a system. Pair this plant with one entry from each other pillar to plan the whole scape.
