Echinodorus tenellus (also known as Helanthium tenellum)

Echinodorus tenellus (also known as Helanthium tenellum) is a bushy aquarium plant. Normally it grows as tall as 10 cm in the aquarium. Leaf width is 3-5 mm or less. It's in many ways similar to Sagittaria subulata, but Sagittaria has slightly larger leaves not less than 5mm wide. Thickets of sagittaria subulata can grow up to 20 cm tall or even more. Echinodorus tenellus becomes smaller and rarely grows more than 5cm tall if kept in poor conditions. However, it can grow even without CO2 and fertilizers. The plant is not demanding in terms of lighting intensity and can be grown in the light of 0.5 watts per liter.

Color of Echinodorus tenellus leaves certainly deserves a separate study. It's known that under medium lighting of 0.5 watts per liter, Echinodorus exhibits green leaves. But under higher lighting intensity leaves can have a gold coloration. Like many other red species of aquatic plants, leaves of Ehinodorus tenellus can achieve red or even purple coloration if grown under lighting of 1 watt per liter or more. The color also depends on the pH level of the aquarium water. If the water is acidic (pH less than 7) echinodorus becomes rather green. While the basic water (pH more than 7) in the aquarium can affect echinodorus in the same way as the high lighting. This is why one can often see Echinodorus tenellus having red leaves in the aquariums with low lighting and no CO2 supply.

Echinodorus tenellus is the most common Echinodorus among aquarists and perhaps the only suitable for aquascaping, thanks to its small size. It easily forms a lawn in the foreground (or rather closer to the midground) of the tank by rapidly spreading its runners. Its very long side shoots should be trimmed once in awhile to keep it from filling in the whole aquarium. This pretty much describes the procedure of how the plant should be pruned and kept within its area. The carpet of Echinodorus tenellus should be also pruned sometimes in a way that it is not growing on top of itself as it may get too tall.