July 25, 2025 3 min read
Micranthemum tweediei "Monte carlo" is popular carpet plant in the aquarium hobby. Its bright green leaves and tight creeping patterns makes it one of the most popular carpeting plants out there. While it is a rather tough plant and adapts to a wide range of growth conditions, it does best in CO2 injected tanks. Regular fertilization and stable parameters are important for long term health.
Monte carlo is best planted in small bunches or single strands. Large bunches have the tendency to float once the plant starts pearling due to photosynthesis. The plant needs to root properly to have a nice carpeting form - this is very closely tied to good planting technique. Monte carlo strands must be planted firmly in the substrate for the plant to grow flat on the substrate rather than upwards. Using smaller clumps and planting individual strands gives a more even carpet that roots well. Planting in clumps that are too large tends to lead to the Monte carlo dislodging from the substrate easily and floating.
Having adequate light (at least 50-60umols of PAR) and adequate CO2 also encourages creeping growth to form.
While Monte carlo can grow in some non CO2 injected tanks, the success rates are not high. Its success rates are very high once CO2 injection is utilized.
Good planting technique makes a huge impact on getting an even carpet. Plant in as small clumps as you can handle.
Having a stable tank that is biologically matured sustains older growth in good form and prevent algae.
It takes awhile for the plant to get established when first planted. Tanks should avoid adding animals that disturb the substrate layer when first planting Monte carlo. Once the plant has rooted and established, it spreads at good speed. Individual strands can be cut and replanted in other areas.
Monte carlo grows into dense mats over time. Due to its tough nature, such mats can keep growing on top of itself for a long time without deteriorating. Eventually the bottoms will deteriorate and the mat may detach from the substrate. Aquarists have two choices: either trim regularly to keep the carpet thin, or leave it to thicken over time, and do a large replanting cycle when the carpet no longer grows healthy top growth because it is too thick. In Monte carlo's case, taking the second option is reasonable as it can grow a very long time without much trimming - just forming a thicker and thicker mat. It may be a time saver to do a big replanting after many months, than to do smaller trimmings every couple of weeks.