A Selection of Natural Habitats (Biotopes)
Just about every aquatic habitat is home to some fish. In freshwater alone, from torrential rainforest streams and high mountain lakes to the deepest freshwater lakes and largest rivers; desert springs and and alpine waters, fish can be found.

Each habitat sees fish with unique adaptations. For instance, the African rapids biotope is home to fish with a modified swim bladder that allows them to stay on the bottom out of the violent current.
We keep fish from all kinds of habitats. The most common freshwater habitats replicated in the aquarium are: rainforest (tropical), rapids, brackish or estuarine, African rift lake.

Within these basic types of habitats are specific biotopes, each containing different fish, water conditions and plant life. For instance, an African rift lake habitat may mimic the rocky shoreline of Lake Malawi with a tank full of Mbuna or the rocky crevices and sandy substrate of Lake Tanganyika, with its Featherfins, sand-sifters and well-known Tropheus.
It may be of interest to you:
Rainforest streams and rivers can be divided into three distinct water types: black water, white water and clear. Each has very different water parameters and even look different. Luckily for us, many fish are comfortable across a range of habitats in the aquarium and many from different natural biotopes will cohabit very well if the water conditions are within their tolerance range and their tank mates are compatible.

If you are keeping fish together that, although one may originate from Asia and another from South America, have the same requirements such as temperature, pH and hardness you should be reasonably OK. Basically, this is what a community tank is – a general mix of fish from different parts of the world all living happily together in your aquarium.
For example, a tropical community tank may have fish including Bolivian Rams (South American), Clown Loaches (Asian), Pearl Gouramies (Asian), Neon Rainbowfish (New Guinea), Guppies (Central American) and African Butterfly Fish (African).

Difficulties start when you try to keep fish from distinctly different habitats together. You are asking for trouble if you try to keep Lake Malawi cichlids (which need hard, alkaline water and slightly lower temperatures) with Amazon blackwater habitat fish like Angelfish (soft, neutral to acid and higher temperatures).
One of these fish will be in water outside their stress tolerance and, while they may live in that tank they will certainly be stressed, showing their unhappiness in dull colours, susceptibility to disease, abnormal behaviour (such as shyness and hiding in normally outgoing fish) and lack of appetite. Also, fish from vastly different habitats do not understand the behaviours of fish from other areas and may be harassed and even killed because they don’t understand the aggression signals or spawning rituals of their tankmates.

You can also choose to go one step further and set up a speciifc rather than general biotope aquarium. This is one that contains only fish and plants that are found together in a single habitat in a single geographic location. This could end up being more specific than the Amazon River or Lake Malawi, but actually mean a specific river or location in the Lake (eg. Tocantins River – South America or Lion Cove – Lake Malawi).
There are advantages to the general biotope. Your choice of plants and fish is not as limited (and availability of plants and fish for some specific biotopes can be a real problem) and it may be easier to achieve a more harmonious and balanced tank.
The links following provide information about the various types of general habitats (eg Lake Malawi, Amazon River) as well as some information about the specific biotopes of those habitats.
Habitats…
- Amazon River
- Lake Malawi
- Lake Tanganyika
- Lake Victoria