Mastering Freshwater Aquarium Ecosystems
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Choosing the Aquarium

Aquarium Dimensions

There are a few things you should take into consideration when choosing an aquarium. The dimensions of the tank, the species of fish you plan to keep, species of plants you may want to keep, and the type of filtration you plan to use. The surface area is the most important factor when choosing an aquarium. Most of the oxygen that enters the water enters at the surface. An aquarium that is 36 in. Length x 12 in. Width x 18 in. Height (90cm x 30cm x 45cm) can hold about the same amount fish as one 36 L x 12 W x 36 H (90cm x 30cm x 90cm).

Fish that are territorial, set up their territory based on the surface area of the bottom or top of the aquarium. Aquariums that are long and wide are the best for heavy stocking. Octagon, hexagon and short/tall aquariums severely limit the number of species of fish you can keep. Often short tanks are only suited for small schooling fish or a pair of territorial fish.

Deep aquariums over 24 inches (60 cm) are more difficult to clean, plant, and decorate. Powerful glass cleaning magnets are usually used on deep aquariums. Deep aquariums should be considered when you plan on keeping large fish.

Aquariums that are wide (front to back) are desirable for planted tanks. Wide tanks allow a depth of field look to the aquarium. Wide tanks allow you to have foreground, middleground, and background plants and decor.

All aquariums should be leveled on the bottom, and be completely in contact with base support. Aquariums that are not level and equally supported across the bottom can break, sometimes after they have been set up for more than a year. Shimming the bottom may be necessary with wood. A ¼ inch sheet of styrofoam can also be used to distribute the weight of an uneven surface.


Glass aquariums have some advantages and disadvantages. Glass aquariums are often less than half the price of a acrylic aquarium. Glass aquariums have some disadvantages as well, they are heavy, have a green tint (unless starfire glass is used), and are not as easy to drill holes for using sump style filtration systems.

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