Fish & Aquariums Freshwater Fish & Aquariums Freshwater Aquarium Basics

Does Aquarium Tank Width Matter?

By
Shirlie Sharpe
Shirlie Sharpe
Shirlie Sharpe is an aquatic expert and writer with over three decades of experience keeping and raising ornamental fish. She has consulted with The Minnesota Zoo and the National Aquarium. Shirlie has also authored a book on setting up aquariums.
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Updated on 07/26/22
Reviewed by
Nick Saint-Erne
Nick Saint-Erne, DVM
Reviewed by Nick Saint-Erne
Dr. Nick Saint-Erne, DVM, is a highly accomplished veterinarian and writer who has treated zoo animals and exotic pets for more than 35 years. He has worked with the Centers for Disease Control and Prevention to improve pet store animal care among other endeavors. Dr. Saint-Erne is part of The Spruce Pets' veterinary review board.
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Hex Tank
Brian Renken

Some say tall narrow aquariums are best, others say wider is better. Is it a personal preference, or is there actually a difference between the size and shape? Personal preference certainly is important, but in tanks of the same water volume, shorter wider tanks do have benefits. Here’s why.

Surface Area

The most important benefit of a wider tank is that it has a larger water surface area. Fish need oxygen just like we do. Oxygen exchange occurs where the water surface meets the air. More water surface area equates to more oxygen exchange, an important factor for the health of your fish. A taller, narrower tank may be striking in appearance, but it has less water surface area than a shorter, wider tank holding the same volume of water.​ The decreased surface area could cause low dissolved oxygen conditions in an overcrowded aquarium!

Habitat

Most fish require room to swim laterally (side to side), which is rather restricted in a tall, narrow tank. This is especially true once plants and other decorations are added, leaving very little open space in a tall tank. Wide tanks allow for an open corridor from side to side that your fish will appreciate.

Another important factor for fish comfort is hiding places. Broader tanks offer more floor space to place rocks, driftwood, and other decorations that fish use as hiding spots. This is particularly important if you keep territorial fish, as they will claim their own space and will not allow other fish to invade their territory. In a tall tank, there is little room for fish to claim their own space.​

Aesthetics

Tall tanks with hexagonal, rectangular, or round shapes can be extremely attractive, at least when they are first set up. Unfortunately, problems occur as the tank matures and algae and debris build up. Cleaning a tall tank is a challenge, especially if they are taller than the length of your arm. Even if your arm is long enough, unusually shaped tanks often have more corners to clean. Round or bowed tanks make the use of magnetic glass cleaners difficult.

Decorating tall tanks is also a challenge, as decorations are generally not tall enough to fill the upper regions of the tank. The result can be less than appealing. Although tall tanks can be successfully decorated and maintained, overall, the shorter, wider tank offers more advantages.