HC Cuba

Water parameters

Light and nutrients

Substrate type: nutrient rich. Propagation: fragmentation.

Substrate compatibility

With fish

Origin and habitat

Native to Cuba, growing in and along shallow, calcareous (hard-water) streams and wet rocky areas. The species (Hemianthus callitrichoides, commonly abbreviated HC or HC Cuba) produces some of the smallest leaves in the aquarium plant hobby: individual leaf pairs are 2–4 mm across on thin, creeping stems. This miniature scale makes it the gold standard for foreground carpeting in competitive aquascaping, creating a lush, verdant lawn effect that no other plant replicates at the same scale. HC Cuba was introduced to the aquarium hobby in the early 2000s by Tropica (the Danish aquatic plant company) after being collected in Cuba, and rapidly became one of the most popular and sought-after plants in the Nature Aquarium style. The plant's small size and demanding requirements make it a benchmark species for judging a planted tank setup's quality.

Care notes

The most demanding common carpeting plant. Requires high light (80+ PAR at substrate level), pressurized CO2 injection (25-35 ppm), and nutrient-rich substrate to carpet successfully. Without all three, the plant grows slowly, develops gaps, and eventually recedes. This is not a low-tech plant; attempts to grow HC Cuba without CO2 almost always fail. Plant small portions from tissue culture cups 1–2 cm apart across the foreground, pressing them firmly into fine-grained substrate (aquasoil or sand). Rich substrate is critical; the tiny roots feed actively. Growth under optimal conditions is moderate: the carpet fills in over 4-6 weeks, with creeping stems branching and overlapping to form a dense mat. Trim with sharp scissors to maintain a uniform height of 1–2 cm. The carpet lifts off the substrate if gas bubbles (from pearling or substrate decomposition) accumulate underneath; press it back down or use a substrate pin. Algae is the primary threat: BBA, green hair algae, and cyanobacteria can overwhelm the slow-growing carpet if CO2, light, and nutrients fall out of balance. Stable, consistent dosing is more important than high dosing. Temperature: 20–28°C. Soft to hard water (the species comes from calcareous water and prefers moderate to high GH, unlike many demanding plants). A rewarding plant for experienced keepers with high-tech setups.

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