“The bigger the aquarium, the easier maintaining it will be.” This is probably the single most important rule in the hobby, and for someone setting up their first aquarium, it is an absolutely essential fact of life. The size of the aquarium has a direct impact on several key physical and chemical processes, including pH stability, thermal stability, and the dilution of metabolic wastes such as ammonia. The smaller the tank, the less stable and the more toxic the environment is likely to be.
The size of the aquarium is also important in terms of how fish behave. Schooling fish need to be kept in groups of at least five or six specimens, and that it turn requires a certain amount of aquarium volume and swimming space. When kept in insufficient numbers, barbs, danios and tetras frustrated and often turn aggressive or nippy. Territorial fish need to be able to claim a certain patch of ground, and if there isn’t enough space in the tank, fighting or bullying can occur. Livebearers pose a particular set of problems because of the way males fight with each other while also tending to the females. It is important that there is enough space for the male and female livebearers to spread out, and if necessary find hiding places where they can rest or give birth safely.
For all practical purposes, the minimum “safe” aquarium size is 20 US gallons (75 litres). Such a tank will be big enough to accommodate a reasonable selection of small aquarium fish without being particularly large or expensive. More ambitious aquarists interested in big or territorial species such as cichlids should consider larger systems though, with tanks up to 55 US gallons (210 litres) in size an2003.com a good balance between size and expense.
