HC Cuba
Micranthemum callitrichoides
Also known asDwarf baby tears · Hemianthus callitrichoides (synonym) · HC
Water parameters
Light and nutrients
Substrate type: nutrient rich. Propagation: fragmentation.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Dirted tank (mineralized topsoil) (DIY soil substrate) | slightly acidic | very high |
With fish
Origin and habitat
A tiny semi-aquatic carpeting plant of the family Linderniaceae, endemic to the West Indies, recorded from the Bahamas, Cuba, the Dominican Republic, Haiti, Jamaica and Puerto Rico, where it grows along shallow streams and damp rocks. The accepted name is Micranthemum callitrichoides; the familiar Hemianthus callitrichoides is a synonym, and in the hobby it is known simply as HC or HC Cuba, or as dwarf baby tears. Its leaf pairs are only 2–4 mm across on thin creeping stems, among the smallest of any aquarium plant, which makes it the benchmark foreground carpet in competitive aquascaping. The aquarium strain was collected at Las Pozas in Cuba in 2003 by Holger Windelov of Tropica and Eusebio Canicio Delgado Perez, and it quickly became a Nature Aquarium icon and a yardstick for tank quality.
Care notes
The most demanding common carpet, and not a low-tech plant. CO2 is essentially mandatory: grown without it the failure rate is around 95 percent. It also wants strong light, roughly 80 PAR at the substrate, and a fine, nutrient-rich substrate such as aquasoil that the delicate roots can penetrate; with all three it carpets in four to six weeks, the creeping stems branching into a dense mat, otherwise it thins and recedes. Plant small portions from tissue-culture cups one to two centimetres apart, pressed firmly in. Trim regularly with sharp scissors, even down near the substrate to clear old growth, because the main cause of the carpet lifting off in sheets is letting it grow too thick, since it builds upward in layers as well as outward; press lifted patches back or pin them. Algae is the constant threat to such a slow carpet, so stable, consistent CO2, light and dosing matter more than high dosing. Keep it warm, around 20–28°C, in soft to moderately hard water. It rewards experienced keepers with high-tech setups. It is an ornamental carpet, not a crop, so it is unsuited to media-bed aquaponics or hydroponics.