FAQ: Plants for fish

Many plants are grown above water for sale, so their leaves are thicker and differently shaped. Once submerged in the aquarium they gradually grow underwater leaves, and the old leaves may die back, which is a normal adjustment.

It is worth it, as plants from another tank can bring snails, their eggs, algae or pests. Inspect and rinse the plants and keep them for a few days in a separate container of water; in vitro plants need no quarantine.

Inspect the plants, pick off snails and egg clusters by hand, then rinse them well with water. Use strong dips only as the manufacturer directs and only on plants that tolerate them; the safest option is in vitro plants.

They can, if the plants were sprayed with pesticides at the nursery, which kill shrimp and snails. To reduce the risk, choose in vitro plants or keep new plants separately for a few days or weeks with water changes before planting.

Strip a few leaves off the bottom of the stem and push each stem separately a few centimetres into the substrate with tweezers. Leave gaps between stems so light reaches the lower leaves and they do not wither.

Rooted plants go in so the roots are in the substrate but the crown or the centre of the rosette stays above it. Stem plants are pushed in a few centimetres, and epiphytes such as anubias and Java fern are not buried at all.

Plants float up when planted too shallow, when the substrate is too coarse or too thin, when fish dig them up or when flow is strong. Plant deeper, weigh them down with a small stone or plant weight until they root, and check whether your fish are digging.

Plants are often sold with lead or other metal strips, which are best removed once the plant has rooted, because the stem can rot beneath them. For the long term, non-metal weights or small stones are safer.

Long tweezers for planting, long straight and curved aquarium scissors for trimming, and a spatula for levelling the substrate are useful. Long tools let you work without putting your hands deep in the water or stirring up the substrate.

In a new aquarium it pays to plant heavily from the start, covering much of the bottom, because dense planting competes better with algae. Part of the area can be filled with fast stem plants that you later replace with slower ones.

Put low plants at the front, medium ones in the middle and tall ones at the back, grouping several of the same species together. Leave open swimming space for fish and combine plants of different colours and leaf shapes for contrast.

It is best to plant right after setting up the substrate and decorations, before adding any fish. Plants help the tank mature, take up ammonia and nitrates and so lower the risk of an algae bloom in the first weeks.

Plants do well in a nutrient-rich aquarium soil, fine gravel or sand over a nutrient base layer, or ordinary substrate with root tabs. Gravel that is too coarse holds roots poorly, while very fine sand can compact.

It is granules made from baked clay or soil, loaded with plant nutrients, and it usually lowers pH and hardness slightly. It suits heavily planted tanks and shrimp, but it gets depleted over time.

Nutrient soil usually feeds plants for anything from a few months to a couple of years, depending on how many plants there are and which kinds. After that it is usually left in place and topped up with root tabs or liquid fertiliser.

Many nutrient soils release ammonia in the first weeks because they contain organic matter. During that time change water often, monitor parameters with tests and add fish and shrimp only once the water has settled, as the manufacturer advises.

Yes, especially epiphytes, floating plants and plants that feed from the water column. Root feeders such as cryptocorynes or Amazon swords need root tabs pushed into the gravel near their roots, and the gravel should be fine, roughly 1–3 mm.

Many plants do grow in sand, especially vallisneria, sagittaria and cryptocorynes, provided they get root tabs. Very fine sand can compact and starve roots of oxygen, so coarser sand of about 1 mm grain suits plants better.

A substrate layer of 5–8 cm is usually enough for plants, and it can be deeper at the back where large plants grow. A layer that is too thin holds roots poorly, while one that is too deep and very fine can stagnate.

It is a layer of nutrients spread under the decorative substrate, usually made of clay, peat or special mixes. It feeds the roots but must not be dug up, so it suits tanks where the fish do not dig.