Is it Better to Have a Tall Fish Tank or a Long Fish Tank?

The shape of a fish can impact the life inside an aquarium in a number of ways. The height-to-width ratio of a fish tank can influence the oxygen level of the tank, the lighting and even the behavior of the fish inside. However, different fish may require different tank shapes.

  1. Oxygen Exchange

    • Active fish like tangs need well-oxygenated water.

      Low, wide aquariums tend to do a better job of exchanging oxygen. Wider aquariums tend to have a greater surface-area-to-volume ratio. Since most oxygen exchange in an aquarium happens at the surface, wider tanks tend to be better oxygenated than taller tanks of the same volume and with the same equipment. However, you can overcome this by artificially increasing the aeration. Adding more water movement with powerhead or airstones can greatly improve the oxygen content of aquarium water.

    Territory

    • African cichlids need room on the bottom of a tank to establish their domain.

      Many aquarium fish like to establish a territory, a patch of the aquarium that belongs to them. Almost all territorial species tend to stake out a space at the bottom of the aquarium. So a wider aquarium gives fish like this more space to call their own, and can allow for more fish to establish territories.

    Maintenance

    • Aquarium require monthly water changes to thrive.

      You also need to consider maintenance when selecting your aquarium. At minimum, you should perform partial water changes monthly. Deeper tanks take more effort to clean. However, this problem is most pronounced on very large aquariums.

    Lighting

    • Coral needs bright light to survive.

      Light attenuates quickly as it moves through water. So if you have organisms that need powerful lighting, like plants or coral, a deeper tank can cause problems. Deeper tanks require more powerful lighting to reach organisms on the bottom. So if you have a planted tank or a reef tank, taller tanks need more expensive lighting and may require more electricity.

    Exceptions

    • Seahorses generally need a tank to themselves.

      In a few situations, you will actually want a deeper tank. Seahorses thrive best in a deep aquarium, due to their vertical body shape. Deep-bodied fish like angelfish and discus fish also prefer deeper aquariums since they have such tall bodies.