February 15, 2023

5 Steps to Tropical Aquarium Success Part 3

Substrate and Decor for your aquarium


The substrate material used in a tank may be purely decorative, or it may serve a particular purpose - such as forming part of the filtration (as in Under-Gravel Filtration) or as a rooting medium for growing plants. The two most commonly used substrate materials are gravel and sand. Gravel is available in a range of sizes from "pea" gravel to fine (2-3mm) size. It is also available in many colours and textures in addition to the "natural" gravel. Pea-sized gravel is probably the most commonly employed; larger sizes can allow debris to fall between the stones where it will decay and affect water quality. For planted tanks, it is often advantageous to use a finer grade of gravel, which should be a lime-free type. Note that many gravels sold for aquarium use are not lime-free unless they specifically say so.

A range of fine-grade sands intended specifically for aquarium use are also available (we don't recommend using less pure types of sand such as builder's sand). Sand is particularly useful for tanks containing bottom feeders with delicate barbels - Corydoras catfish, for example, seem to enjoy rooting around in the sandy substrate for food. It is generally easy to keep clean as debris remains on top of the sand. Sand should not be used with an undergravel filtration system as the particle size is too small.

Some manufacturers produce special substrates for use in planted tanks. Some are designed to be mixed with or placed below gravel or sand, whilst others can be used alone. They are usually clay-based and rich in iron and other nutrients and trace elements required by plants.

Despite the more natural feel provided by a gravel or sand substrate, there are some situations where it may be preferable to omit the substrate altogether. These include tanks for fry-rearing and isolation/quarantine tanks, where the tank needs to be easy to clean thoroughly.

Aquarium Decor

The décor chosen for aquascaping an aquarium is of course very much a case of personal taste. As long as the décor is non-toxic and safe for fish, then the only limit is your imagination!

The choice of décor greatly influences the final appearance of the tank, and it’s worth taking time to plan the tank layout and consider how you want it to look. The decor may be only for decorative purposes, but will often serve as refuges for fish to make them feel more secure. Some decor may also influence the water chemistry (e.g. coral sand).


Rocks are a very useful item for decorating the aquarium. They break up the aquascape and can be used to provide refuges in the form of caves. In some tanks, such as those designed for African Rift Lake cichlids, they may constitute the main or only decor. In such tanks, a large wall or pile of rocks is built to form many caves and niches in the rock to serve as places to hide from aggressive tank mates, and for use as spawning caves.

A number of different rocks are suitable for aquarium use. Some, such as slate and lava rock, are inert and should be safe for use in any aquarium. Others, including limestone and the crumbly tufa rock, can release hardening salts into the water and should only be used in hard-water setups.


Bogwood or driftwood makes a very attractive addition to the aquascape. Its colour contrasts well with green plants. It provides a natural looking refuge for fish. Many suckermouth catfish in particular like to rest on bogwood - many species rasp at the wood and use it like fibre in their diet, and some species even derive nutrition from it.

Before use bogwood should be soaked (preferably for a few weeks changing water frequently) and then rinsed, to allow some of the colour and organic acids to leach. The organic acids and even the colouration released by bogwood may be desirable in certain setups, e.g. South American "Amazon" style tanks, where the "blackwater" effect is desired. However, the leaching may be very heavy at first if not pre-soaked, and although the substances released are not actually directly harmful (in fact they are often beneficial to fish and plants), they can discolour the water considerably, and could lead to undesirably low pH levels in some setups.

More branching forms of wood are also available, sometimes known as redmoor wood. This wood can produce very decorative effects and does not usually release as much colour as bogwood. It may still require pre-soaking however, especially to get it to sink initially.

Artificial Plants

While not considered as desirable or attractive as the real thing, plastic plants do perform useful functions in an aquarium. Firstly, they provide shelter and security for fish. They also serve as an additional surface for colonisation by the ‘friendly‘ bacteria that break down wastes. They do have the advantage that they require less maintenance than real plants and can be removed and cleaned! Some of the newer types are quite realistic - silk plants, for instance, tend to move fairly naturally in the current.

Real Plants

Real plants are the ultimate in aquarium decor, a well planted tank is a stunning site. They also contribute to maintaining a balanced water chemistry in the aquarium and oxygenate the water during the day. There is of course a price to pay for these advantages - a well planted tank does require some extra maintenance to continue to look its best, but a little bit of pruning and tidying about once a week is usually all that’s required.

It is necessary to provide the correct lighting conditions, and some more demanding plants may require a nutrient substrate and/or liquid fertilizer to thrive, or even CO2 injection. There are, however, a number of fast-growing plants which are not too demanding, and which can add to the appearance of any tank. At Wharf we have fresh aquarium plants delivered every week, and offer both bunched plants and high-quality potted plants.

Introduction Equipment Tank Decor Adding Fish Maintenance