HC 'Cuba' (Micranthemum callitrichoides): grower data
One of the smallest aquarium plants, with millimeter-sized leaves, rated advanced by Tropica with high light and high CO2 demand [1]. Tropica suggests Monte Carlo as a less demanding alternative when good light, CO2, circulation and fertilizer are hard to provide [1].
Grower data
As published by Tropica Aquarium Plants[1]
- Light demand
- HighTropica: medium light demand is 0.5 W/L.
- CO2 demand
- HighTropica: medium need 6–14 mg/L; high approx. 15–25 mg/L.
- Growth rate
- Medium
- Difficulty
- Advanced
| Type | Carpeting |
|---|---|
| Origin (grower) | North America |
| Height after two months | 3 - 5+ cm |
| Placement | foreground[3] |
| Difficulty (second grower) | Difficult[3] |
| Care height (second grower) | 1–3 cm[3] |
| Water hardness (maximum) | Hard[3] |
| CO2 needed (second grower) | Yes[3] |
Name and range
- Accepted name
- Micranthemum callitrichoides (Griseb.) C.Wright[6]
- Family
- Linderniaceae
- Native range
- Bahamas, Cuba, Dominican Republic, Haiti, Jamaica, Puerto Rico
- Records
- WCVP via GBIF and POWO
What the grower data says
This is the demanding end of the scale. Tropica rates HC ‘Cuba’ advanced, with high light and high CO2 demand and medium growth [1]; Aquasabi rates it difficult, with high light and CO2 required [3]. Tropica’s plant pages define a high CO2 need as approximately 15–25 mg/L [1], and its fertilizer guide puts advanced plants at 15–30 mg/L [4]. The CO2 calculator shows the pH that corresponds to those levels at your KH.
Tropica’s description is more nuanced than the rating. It says HC is “not a difficult plant”, but that it needs good conditions to thrive: enough light, added CO2, water circulation and fertilizer [1]. Where those are hard to provide, Tropica suggests Monte Carlo as a less demanding alternative [1], a recommendation that matches its trial results, in which Monte Carlo grew much like HC but proved more adaptable [5].
Size
Tropica calls it one of the smallest aquarium plants in the world, creeping over the bottom with round leaves a millimeter or so across [1]. Aquasabi gives a care height of 1–3 cm [3], and Tropica’s rating is 3–5 cm [1].
Planting and carpet care
Aquasabi lists it for the foreground and nano tanks [3]. Tropica’s method is to plant small clumps a few centimeters apart, from which it spreads rapidly to cover the bottom [1].
The carpet needs regular trimming. Tropica explains why: without it the lower parts do not get enough light, which causes root death [1]. Tropica also notes that small pearls or bubbles of oxygen are often produced on top of the plants [1].
Names and taxonomy
Tropica’s two listings use two names for the same plant: Micranthemum callitrichoides ‘Cuba’ on one, Hemianthus callitrichoides on the other [1, 2]. The World Checklist of Vascular Plants settles it: it accepts Micranthemum callitrichoides (Griseb.) C.Wright in the family Linderniaceae and lists Hemianthus callitrichoides Griseb. as a synonym, among 16 [6].
Tropica says the plant was found on Cuba, west of Havana [1], and its origin field reads “North America”. WCVP’s native range is the Caribbean: Cuba, Jamaica, Hispaniola (Haiti and the Dominican Republic), Puerto Rico and the Bahamas [6, 7].
Questions
How much CO2 does HC 'Cuba' need?
Tropica rates its CO2 need high, which its plant pages define as approximately 15–25 mg/L [1]; its fertilizer guide gives 15–30 mg/L for plants in the advanced group [4].
Why does my HC carpet come loose from the substrate?
Tropica says the carpet must be trimmed regularly, otherwise the lower parts do not get enough light, which causes root death [1].
Similar plants
- Dwarf hairgrass (Eleocharis acicularis): grower datacarpeting, foreground / midgroundLight: LowCO2: LowEasy
- Glossostigma elatinoides: grower data for a demanding carpetcarpeting, foregroundLight: HighCO2: HighAdvanced
- Monte Carlo (Micranthemum 'Monte Carlo'): grower data and historycarpeting, foregroundLight: MediumCO2: MediumMedium
Related guides
- CO2 & lightCO2 from KH and pH: the formula, the chart and where it breaksWhere the KH/pH/CO2 chart comes from, why its factor of 3 differs from the temperature-corrected 3.5, and the conditions under which both estimates fail.
- CO2 & lightPAR, PPFD and DLI: the light units that matter to plantsWhat PAR, PPFD and DLI measure, why lux, lumens and watts do not describe light for photosynthesis, and how to turn a PPFD reading and a photoperiod into a DLI.
- CO2 & lightWhat low, medium and high light and CO2 mean in grower plant dataTropica's light and CO2 ratings, the definitions behind them, the three different CO2 bands on its own pages, and how Aquasabi's categories line up.
Compare it with the other profiled plants in the plant parameter table.
Sources
- Micranthemum callitrichoides ´Cuba´ (plant details, 048B). Tropica Aquarium Plants. Type, origin, growth, height, light, CO2 and difficulty; description: one of the smallest aquarium plants, needs light, CO2, circulation and fertilizer, plant small clumps a few cm apart, trim the carpet, found on Cuba west of Havana; Monte Carlo as an alternative. Accessed October 12, 2026.
- Micranthemum callitrichoides 'Cuba' (plant details, 048BTC tissue culture). Tropica Aquarium Plants. The same description under the older name Hemianthus callitrichoides. Accessed October 12, 2026.
- Hemianthus callitrichoides 'Cuba' (Aquarium Plant Profile). Aquasabi. Placement: nano aquarium, foreground; difficult; medium growth; high light; hardness up to hard; 1–3 cm; CO2 yes. Accessed October 12, 2026.
- Fertiliser and CO2. Tropica Aquarium Plants. Advanced plants require 15–30 mg/L CO2. Accessed October 12, 2026.
- Micranthemum 'Monte Carlo' (article by George Farmer, 17 May 2020). Tropica Aquarium Plants. Monte Carlo grew like HC 'Cuba' in Tropica's trials but was more adaptable and easier. Accessed October 12, 2026.
- Micranthemum callitrichoides (Griseb.) C.Wright: World Checklist of Vascular Plants record (via GBIF). Royal Botanic Gardens, Kew; dataset published 2026-06-04, CC BY 4.0. Accepted name, family, synonyms, native and introduced range. Accessed October 12, 2026.
- Micranthemum callitrichoides: Plants of the World Online. Royal Botanic Gardens, Kew. Addressed by IPNI identifier 805796-1; POWO displays the same WCVP data. Accessed October 12, 2026.