FAQ: Plants for fish

Live aquarium plants absorb nitrates, release oxygen and compete with algae, but they need light, fertiliser and care. Artificial plants need no care, but they do nothing for water quality.

Most live aquarium plants benefit from fertiliser, because fish waste rarely supplies every nutrient. Whether and how much to fertilise depends on the plant species, how strong the lighting is and the substrate.

Live plants give fish hiding and spawning places, reduce stress, take up some ammonia and nitrate and add oxygen to the water during the day. In a densely planted tank there are fewer nutrients left for algae.

Yes, in the dark plants respire and use a little oxygen, but in a normal aquarium this does not endanger the fish. If the tank is very densely planted and heavily stocked, an air pump at night can help.

Yes, it is a common approach: artificial plants fill spots where live ones lack light, while live plants improve water quality. Make sure the artificial plants are made for aquariums and have no sharp edges.

Yes, provided there is a suitable filter, regular water changes and hiding places for the fish. Without plants, though, nitrates build up faster, so water usually needs changing more often and algae take hold more easily.

Undemanding plants suit beginners: anubias, Java fern, cryptocorynes, Java moss, vallisneria, hygrophila and hornwort. They grow under weak lighting, without CO2, and tolerate swings in water parameters.

Anubias, Java fern, bucephalandra, cryptocorynes, mosses, vallisneria and most floating plants grow well without CO2 under moderate lighting. They grow more slowly, so they also need less fertiliser.

Stem and floating plants grow fastest: hygrophila, hornwort, cabomba, limnophila, elodea, salvinia and duckweed. They take up nutrients quickly, so they help fight algae in a new aquarium.

Anubias, Java fern, bucephalandra and most cryptocorynes grow slowly. Their leaves last a long time, so algae settle on them more easily, which is why these plants are best placed away from the strongest light.

Never bury the anubias rhizome in the substrate, as it will rot. Tie or glue the plant to a rock or wood, keep it in a shaded spot and wipe algae off the leaves now and then.

Java fern grows attached to surfaces, so tie it to wood or rock with fishing line or cotton thread, or glue it with aquarium-safe glue. Within a few weeks the roots will grip on their own.

Black patches on Java fern leaves are often linked to a lack of nutrients, especially potassium, to light that is too strong, or to a buried rhizome. Old leaves also often grow new plantlets, which can be separated.

Tie Java moss with fine thread onto a rock, wood or mesh. It grows even in low light but likes clean water with some flow, so trim it regularly and rinse out debris that collects in it.

Yes, cryptocorynes are undemanding about light and grow without CO2, but they need a nutrient-rich substrate or root tabs. After being moved they often drop their leaves, but they usually regrow from the roots.

Plant vallisneria so the crown stays just above the substrate. It spreads by runners, suits the background and does well in harder water, and leaves that reach the surface can be trimmed.

Marimo are ball-shaped green algae that grow slowly and prefer cooler water and gentle light. Every few weeks roll them around and gently squeeze them under water so they keep their shape and stay clean.

The Amazon sword grows large, so it needs a roomy tank and a place in the background. It takes most of its food through the roots, so it benefits from a nutrient-rich substrate or root tabs placed near the roots.

Low plants suit the foreground: small cryptocorynes, hairgrass, sagittaria, dwarf anubias, mosses and carpeting plants. They do not block the view and create a sense of depth.

Tall plants suit the background: vallisneria, stem plants such as hygrophila, ludwigia or rotala, cabomba and large Amazon swords. They hide equipment and form a backdrop for lower plants.