Live plants provide more than just an aesthetic function in the aquarium, although this could be considered their main function. Plants also provide an equally important function in providing the fish with natural hiding places, surroundings and in some cases sources of food. Fish that originate in areas of dense vegetation will often suffer in aquariums without a suitable number of plants. The positive effects of a healthy and well-planted aquarium can be seen in the increased colour and activity of the fish.

Plants and water quality
Live plants also provide a service to the aquarium and its inhabitants by acting as a filter and removing dangerous compounds. Plants have a natural ability to absorb metals and pollutants, many of which are used by the plants as a source of nutrients. This is particularly useful in aquariums that are supplied by tapwater. Many tapwater sources contain large amounts of metal compounds, which although not dangerous to humans, may damage fish after a long exposure. Nitrates are one such chemical, although nitrates occur as a result of the biological filtration process as well as from tapwater. Over time nitrates in the aquarium can build up to dangerous levels if sufficient water changes are not carried out. Plants use nitrates as a major source of nitrogen, which is vital for plant growth. A well-planted aquarium rarely has high nitrate levels, unless they have been artificially introduced.

Plants and fish in the aquarium
Plants provide many benefits for fishes, although fishes should be chosen carefully for a planted aquarium. Many fish species, especially some larger characins, barbs and cichlids can cause problems for aquarium plants. Some of these fish may be natural herbivores, consuming plants with ease, whilst others may simply be boisterous and destructive.
Fishes can also benefit aquarium plants, many smaller catfish and loaches provide a service to aquarium plants by removing algae from leaves and disturbing debris caught amongst the leaves and stems. In general plants will mix well with smaller fish whilst larger species may only mix with certain hardy or tougher leaved plants.

The difficulty of keeping plants
Although the effects of live plants are certainly beneficial to the aquarium, large majorities of fishkeepers have trouble in keeping a healthy selection of plants. The underlying reason for this is that a 'standard' aquarium setup is designed for the needs of the fishes and not for the requirements of plants. To keep plants successfully they must be provided with a suitable substrate, lighting and nutrient requirements. The standard aquarium often falls short of these requirements and a lack of nutrients and excess water movement in the substrate makes it difficult for plants to stay alive and healthy. A few hardy species of plants can be kept in aquariums with a minimal amount of additional care. A well-planted aquarium with a number of varieties however, will require a little bit more attention. The care of a heavily planted and well aquascaped aquarium will focus mainly on the plants. If the plants needs are provided for, then the fish, with regular feeding, will largely look after themselves.

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