FAQ: Plants for fish

Most tropical aquarium plants grow best in water at 22–28 °C. At higher temperatures growth speeds up but oxygen and CO2 drop, while in cooler water plants grow more slowly.

Most aquarium plants adapt to a range of hardness, but some, especially more demanding stem and red plants, grow better in soft water. Vallisneria and anubias tolerate hard water well.

Usually yes, if it is prepared for the aquarium, for example with chlorine neutralised. In Lithuania tap water is often hard, so for soft-water plants it is sometimes mixed with reverse osmosis water.

Pure RO water lacks the minerals plants and fish need, so it is mixed with tap water or remineralised with special additives. That way you can reach the hardness you want for soft-water plants or shrimp.

Regular water changes remove excess nitrate and restore minerals, so they are usually good for plants. The new water should match in temperature and parameters, because sudden changes can trigger cryptocoryne melt.

Moderate flow is good for plants because it spreads fertiliser and CO2 and stops debris settling on leaves. Flow that is too strong can break delicate plants, while flow that is too weak encourages algae and black beard algae.

Right after a heavy trim, plants temporarily use fewer nutrients, which can lead to more algae. Trim gradually, and after a big trim reduce the fertiliser dose for a while and change some water.

Before leaving, trim the plants, change the water, clean the filter and set the light timer. For a couple of weeks fertilising can be reduced or paused, and it is worth turning the CO2 down so there is no risk to fish while unattended.

Pack the plants in bags or boxes with a little tank water or damp paper towels so they do not dry out, and protect them from heat and cold. For a short move, plants usually survive a few days in a moist environment.

In winter plants can freeze in transit, so ask whether the shop packs them with a heat pack or insulation. When the parcel arrives, unpack it straight away and put the plants into room-temperature water.

Keep the plants in a container of tank or prepared water, somewhere warm and bright but not in direct sun. In pots or in vitro cups they can last a few days, but the sooner you plant them, the more easily they establish.

A low-tech tank uses moderate light, little fertiliser and no CO2, so it grows undemanding plants with little upkeep. A high-tech tank uses strong light, CO2 and regular fertilising to grow demanding plants, but takes more work.

In the Dutch style the tank is planted with dense groups of plants with strongly contrasting colours and leaf shapes, like an underwater garden, with hardly any rock or wood. It needs many stem plants, frequent trimming and usually CO2.

Iwagumi is a style of Japanese origin built around a few rocks, with the bottom planted with one or a few carpeting species. It looks minimalist but is demanding: it needs strong lighting, CO2 and strict algae control.

In the jungle style plants are left to grow freely and densely, with floating plants, roots and branches, so the tank looks like wild nature. Undemanding plants suit this style well and it needs less trimming.

The Walstad method is a tank with soil under a sand cap, lots of plants, few fish and minimal equipment, sometimes without a filter. The plants keep the water quality up themselves, but the method takes patience and does not suit all fish.

With a dry start, carpeting plants are planted in moist substrate that is not flooded, and the tank is covered with film. After a few weeks, once the plants have rooted and thickened, the tank is filled with water, with a lower risk of algae.

Arrange the wood and rocks first, then plant around them, hiding their bases and creating a transition between the decor and the substrate. Tie epiphytes directly onto the wood or rocks, and plant tall plants behind them.

Tall background plants such as vallisneria or stem plants, and moss tied onto pipes, will hide the filter, heater and tubing. Leave space around the equipment so plants do not block the filter intake or touch the heater.

Bucephalandra grows very slowly, so attach it to rocks or wood like anubias, without burying the rhizome. It likes moderate light and clean water with some flow, and its slow leaves need protecting from algae.