Tanks

Choosing the right tank size is one of the most important aspects of fishkeeping. While fish might survive in a smaller tank, they won't thrive. To put it in perspective, you could survive in an elevator, but living there long term would be far from ideal. Fish need space to exhibit natural behaviors and to live comfortably.

As a general rule of thumb for freshwater fish, provide 5 gallons of water for every inch of the biggest fish’s typical adult size. For example, a 6-inch freshwater fish would need at least a 30-gallon tank. Saltwater fish, due to their more active nature, need a tank that is 6 to 12 times their adult size in length. So, for a 6-inch saltwater fish, you would need a tank that is 3 to 6 feet long (typically a 40-gallon breeder to a 125-gallon tank). While there are exceptions to these guidelines, they apply to most fish and will help ensure your fish have enough room to grow and thrive.

Bigger Tanks = Happier Fish

A larger tank is always preferable, as it provides a more stable environment. While it may seem like more work to maintain a larger tank, the maintenance doesn't scale linearly with tank size. For instance, maintaining a 200-gallon tank isn’t as much harder than maintaining a 10-gallon tank as you might expect. Water chemistry in larger tanks is also more stable, meaning that small fluctuations have a less dramatic effect. Even a small change in water parameters can cause stress in a small tank, but in a larger tank, those changes are less impactful.

Additionally, just because a fish can survive in a smaller tank doesn’t mean it will thrive. A Betta, for example, might live in a 5-gallon tank, but it will be much happier and healthier in a 75-gallon tank, with more space to swim and exhibit natural behaviors.

Tank Types: Glass, Acrylic, and All-In-One Options

Glass Tanks

Glass is the most common material for small to medium-sized aquariums. It’s scratch-resistant, easy to clean, and durable, making it a great option for tanks under 100 gallons. When buying a used tank, especially for saltwater setups, you can benefit from purchasing a mature system, but be cautious. Used tanks may not have a warranty, and some may have been drilled for a sump or resealed, potentially compromising the tank’s integrity.

Avoid buying tanks that are chipped or cracked—water weighs roughly 8 pounds per gallon for freshwater and 9 pounds for saltwater. Even small chips can lead to microfractures that could cause the tank to fail under pressure, much like a windshield chip that spreads over time. It’s always better to err on the side of caution when dealing with glass tanks.

Acrylic Tanks

Acrylic is a popular choice for larger aquariums due to its lightweight nature and ability to remain clear even at larger thicknesses. Acrylic tanks are easier to drill and modify compared to glass tanks, which makes them ideal for custom setups like sumps. However, acrylic can scratch more easily than glass, making cleaning a bit more of a chore. The benefit is that scratches can be buffed out, and soft materials like used credit cards can be used for scraping without damaging the surface.

Acrylic tanks are generally more expensive and harder to find, but they offer a seamless design, which reduces the potential for leaks. If you’re planning to invest in a larger tank, acrylic might be the best option due to its strength and flexibility.

All-in-One (AIO) Tanks

All-in-one tanks combine the main tank with a built-in filtration system, often using a divided space where water flows through different types of media, similar to a sump. These are especially popular for saltwater aquariums, where precise filtration is crucial. AIO tanks are a great option if you’re concerned about leaks and want a more compact, efficient filtration system without the hassle of external sumps.