Aquarium mosses

Java, Christmas and Taiwan moss carpet a piece of wood or a mesh pad. Flame moss grows upward in twisted strands and makes vertical accents. Weeping moss hangs down from a branch. Christmas and peacock moss on a bonsai branch make the tree-shaped scapes. Mini fissidens, nano moss and mini pellia cushion a rock in a nano tank. For fry and shrimp any of them will do, and java moss does it cheapest. Riccia is the odd one out: it wants high light and CO2, and it floats unless it is tied down, but tied to a stone in a bright tank it makes the brightest green carpet in the hobby.

Spread the moss thin over wood, rock or a stainless mesh pad and tie it with cotton thread or a hairnet, or use dots of super glue gel; it grips in three to six weeks and the thread rots away. Thin is the whole trick. A thick wad shades its own base, the bottom layer dies, and the clump lifts off in one piece. Trim it back hard every few weeks, blow the debris out of it with a turkey baster at water-change time, and it stays dense and attached. Never bury moss.

Every moss but riccia lists low or medium light and no or beneficial CO2. The enemy is not the moss dying but algae growing in it, and more light makes that worse faster than it makes the moss grow. Keep the light modest, keep flow moderate so debris does not settle, and keep shrimp: a colony of cherry or amano shrimp is the most reliable way to keep hair algae out of a moss scape. Most mosses list 59–86°F (15–30°C); the Fissidens list narrower ranges within that, willow moss goes down to 50°F (10°C) and stringy moss to near freezing.

The marimo moss ball is a ball of green alga, and it wants cool water, low light and a turn every week or two so all sides get light; it is marked beginner and takes water from 39°F (4°C). Pellia and mini pellia are liverworts with flat, branching lobes rather than leaves; pellia is slow and easy in low light, and mini pellia, marked medium and wanting a little more light, is the classic rock cushion for a nano tank. Süsswassertang looks like a green seaweed and grows as a loose thicket that shrimp live in. Riccia floats by nature and is the one member of this list that lists high light and CO2 required. None of them care what you call them.