Fish tanks can be dynamic additions to your home decor while serving as the perfect home for your aquatic pets. Because the aquarium you choose will be the habitat for all of your fish, it's crucial to understand how its dimensions can impact their health and quality of life. Keep reading for a comprehensive breakdown on fish tank sizes and types, so you can make the perfect selection.

Common Fish Tank Sizes
Aquarium Capacity & Corresponding Weights
Which Type of Fish Tank Should I Choose?
Which Is Better: Saltwater vs. Freshwater?
Which Fish Tank Material Is Best?

Common Fish Tank Sizes

Generally, it’s recommended to choose an aquarium size that can hold one gallon of water per inch of fish. Though this guideline is a good spot to start, be sure to do your research on your specific types of fish to make sure you are providing the proper environment for them.

Fish tanks come in a variety of sizes, so you can select one that meets your capacity needs. Here is an overview of the most common fish tank sizes based on their gallon capacities.

Up to 10 Gallons

Professionals recommend 5-gallon tanks as the minimum aquarium size for just one fish. This prevents fluctuations in pH and prevents buildups of chemicals or waste materials. This size also ensures a healthy gas exchange and gives fish enough room to swim.

11–20 Gallons

Tanks that hold 11 to 20 gallons of water are affordable and perfect for fish owners looking for tanks that won't take up too much space. These sizes can be decorative and are often used as home decor.

20-gallon tanks can comfortably house a handful of smaller fish. These tanks require careful maintenance to ensure proper filtration and chemical balance. If you're a beginner looking for an aquarium size to hold approximately a half dozen fish under 3" in length, this size may be the perfect fit.

21–40 Gallons

Aquarium dimensions that range between 21 and 40 gallons are optimal for keeping approximately half a dozen to a dozen small fish healthy and happy. This volume ensures that water quality stays safe, and requires maintenance a bit less frequently. Larger tanks also make great conversation pieces in living spaces, dining rooms, or entryways.

Over 40 Gallons

Aquariums that hold 40 gallons or more are optimal for comfortably housing a large, diverse range of fish. They’re striking focal points, and many of these selections come with built-in stands. Measure your home to be sure that the aquarium’s dimensions properly fit your space.

Aquarium Capacity & Corresponding Weights

One of the most important metrics to keep in mind when buying an aquarium or fish tank is its weight when filled with water and substrate (the sand or gravel layer on the bottom of the tank). While an aquarium's dimensions may make it the appropriate size for a table or stand in your home, its filled weight may require more support.

A single gallon of water weighs approximately 8.34 pounds, which means 180-gallon aquariums can weigh over a ton. Take a look at the fish tank size chart above for a quick overview of how much water weight corresponds to each aquarium capacity. The above chart displays each aquarium size’s weight when filled to the brim with water. Consider choosing a fish tank with a stand included to ensure your aquarium has enough support.

Additional Fish Tank Considerations

In addition to size, it’s important to consider which fish tank is best suited for your space and your new pet.

Which Type of Fish Tank Should I Choose?

From large aquariums to small space–friendly starter kits, there are a few different types of fish tanks to choose from.

• Aquarium/Tank: These transparent tanks are made of glass or acrylic, and come in a wide range of sizes and shapes.

• Fish Bowl: With a small bowl-shaped silhouette, this option is a decorative selection best suited for one or two small fish.

• Starter Kit: Starter kits include everything you'll need to start your own aquarium. These kits typically come with an aquarium tank and essentials like gravel, a filtration system, and lighting.

Which Is Better: Saltwater vs. Freshwater

Next, it’s time to choose between a freshwater and saltwater tank.

• Saltwater: Saltwater tanks require special filtration, so it's important to make sure your selection is large enough to accommodate a filter and properly fits within your space. Common species of saltwater fish are clownfish, gobies, green chromis, or cardinalfish.

• Freshwater: Freshwater tanks are easy to clean and cost less upfront, making them a great selection for first-time fish owners. Popular types of freshwater fish include bettas, goldfish, tetras, and cichlids.

• Saltwater & Freshwater: These versatile fish tanks are suitable for either freshwater or saltwater fish, and can be adapted to fit the needs of either species. This is a great option if you aren't sure which type of fish you’d like, or if you want flexibility for future use.

Which Fish Tank Material Is Best?

Material is another key consideration choosing a fish tank. Keep reading to explore some of the most popular options.

Aquarium Materials

Glass and acrylic are the two main aquarium materials to choose from.

• Glass: Glass aquariums are affordable and easy to clean. They may be more fragile and come in fewer designs than acrylic aquariums, but are often more durable and scratch-resistant. If you choose a glass aquarium, place it on a flat surface large enough to accommodate the entire base – this prevents any uneven weight distribution that may cause cracking.

• Acrylic: Acrylic aquariums are lighter than glass options and available in plenty of designs. Though they are more prone to scratching, this is a shatterproof option about 17 times more durable than glass. The increased sturdiness and lightweight design often make acrylic tanks more expensive yet a worthwhile investment.

Base Materials

Fish tank bases are designed to support the weight of the aquarium, and often feature cabinets below to store pet care and cleaning supplies.

• Metal: Metal aquarium bases are strong, reliable, and long-lasting. These durable selections are often made from steel or aluminum, and can be more expensive than wood bases.

• Wood: Wood aquarium bases are versatile in design, and typically painted or sealed to avoid warping or water damage.

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