Probably the most important decision is the tank you buy; this affects the amount of fish you can keep and the actual type of fish.
Tanks come in a range of sizes and shapes and there is one to suit everyone in store. Be careful which fish you buy as very similar sized juveniles can grow into vastly differing sized adults. The shape of tank will need to correspond with the habits of fish you buy. Bottom feeders like Catfish, Cory and Loach require lots of horizontal space to move and feed. This is less necessary with mid to upper water fish like Neon tetra, Mollies, Guppies and Goldfish which like vertical space to patrol in the tank. The tank also needs to suit your home and will add colour and interest to any room it is placed in. A tall but narrow tank may take up less space in the house but will hold less fish in the same volume of water as a shorter but wider tank. This is due to the amount of water in contact with the air allowing for aeration. A good filter can correct this problem. A correct stand is also important with bigger tanks due to the weight of water which needs supporting.
A ‘2 foot’ tank, usually 0.6m x 0.3m x 0.2m contains about 35l of water weighing about 35kg. A ‘3 foot’ tank will weigh over 50kg when full.
The amount of light is not only important for the fish and plants within the tank but also for easy viewing and to bring out the bright and vibrant colours of fish. Plants in the aquarium need light to photosynthesise and will die without sufficient levels. There are several types of light available, most are fluorescent tubes inside the hood of the tank. Tropical fish need more light than Temperate. Marine tanks are best lit with mercury vapour lamps or high intensity halide lamps that produce more light. Tanks that are particularly deep or have lots of plants need additional lighting.
Filter and Aeration
As the number and size of fish in a tank increases so do the demands on oxygen and nitrogen levels in the tank. Choosing the right filter size for your tank will allow a good supply of oxygen and will remove excess nitrogen from the faeces and food left by the fish. This is essential in lowering the risk of both bacterial and fungal infection within the tank. Some species require more oxygen and cleaner water than others and this in turn affects which filter you must buy.
This isn’t necessary for temperate species such as Goldfish but is needed for Tropical and Marine tanks. The standard temperature within tropical and marine tanks should be about 25 Degrees Celsius although some fish require slight variations on this. The size and output of the heaters needs to be matched to the size of the tank. Modern heaters incorporate a digital thermostat, these are very reliable, but it is a good idea to have an external or internal thermometer to keep an eye on the temperature and help with the initial setting.