Monte Carlo

Water parameters

Light and nutrients

Substrate type: nutrient rich. Propagation: fragmentation.

Substrate compatibility

With fish

Origin and habitat

Native to Argentina, growing in wet, rocky areas along riverbanks and in shallow water. The species (Micranthemum tweediei, formerly listed as Micranthemum sp. 'Monte Carlo') was introduced to the aquarium hobby around 2013 from collections near the Monte Carlo municipality in Argentina. The plant produces small, round, bright green leaves (3–5 mm) on creeping stems that root at each node, forming a dense, low carpet. Monte Carlo quickly became one of the most popular carpeting plants in aquascaping because it carpets more easily than HC Cuba while producing a similar visual effect at only slightly larger scale. The rapid adoption of Monte Carlo in competitive aquascaping reflects its exceptional balance of ease and aesthetics. It has largely displaced HC Cuba as the default carpet choice in intermediate-level planted tanks. Available as tissue culture cups from most aquatic plant producers. The relatively recent introduction means its long-term behavior in different water chemistries is still being explored by hobbyists.

Care notes

The most practical carpeting plant for medium to high-tech setups. Easier than HC Cuba (less demanding about CO2 and light levels), faster than Marsilea hirsuta, and produces a denser carpet than dwarf sagittaria. Moderate to high light and CO2 injection are recommended for the tightest, lowest-growing carpet. Without CO2, the plant still grows but carpets more slowly and may grow taller and less compact. Rich substrate supports the vigorous root system; aquasoil or a capped nutrient layer produces the best results. Plant small portions from tissue culture cups 2–3 cm apart across the foreground, pressing them into the substrate. Growth under optimal conditions is moderate to fast: the carpet fills in over 4-8 weeks. Trim the carpet with scissors to maintain a height of 1–3 cm; trimming promotes horizontal creeping and denser coverage. The carpet can lift from the substrate if gas bubbles accumulate underneath; press it back down. Temperature: 20–26°C. pH 6.0-7.5. Soft to moderately hard water. Algae is less of a problem than with HC Cuba because Monte Carlo grows faster, but balance is still needed. For most aquascapers, Monte Carlo has replaced HC Cuba as the go-to carpeting plant because it delivers 90% of the visual impact with 60% of the difficulty.

Further reading

• Carpeting plants that don't need CO2
• CO2 injection for planted tanks: what it costs, what it does, and when to skip it