If you're thinking about setting up an aquarium, or you've already made the decision to start shopping, one of the first things you're probably considering is what size fish tank to get. If this is your first experience with an aquarium, you might be thinking that it's best to start out with a smaller size. You might think that it will keep the cost down and that smaller aquariums are less intimidating. Not to mention, they don't take up as much space.
While this line of thinking may seem logical, the opposite is actually true. Yes, a larger aquarium will cost more, but bigger tanks are easier to take care of and are far more forgiving of beginner mistakes. Many first-time aquarium owners quickly grow out of their first aquariums and find themselves wishing they had started out with a larger one.
Newly set up aquariums are unstable biologically. Toxic ammonia and nitrite levels can rise, stressing or even killing fish. In smaller aquariums, these levels rise more rapidly and to much more dangerous concentrations. You won't have as much time to take action to correct the water issues. Unfortunately, one of the first signs of trouble is fish dying. With a larger volume of water, however, things happen more gradually, and you will have more time to implement some possible solutions.
Another consideration are the dimensions of your new tank. Believe it or not, different fish prefer different shapes and swimming spaces!
Active fish like danios and barbs need longer aquariums which means a rectangular design with more horizontal space will suit them well. Territorial fish, like cichlids, need lots of bottom space so stay away from narrow or taller aquariums if you plan on keeping this type of fish. But there are fish that prefer tall and narrow fish tanks, too. They can be ideal for less active fish like discus, angelfish and gouramis. While the tall, narrow shape doesn't offer as much swimming area or surface area for gas exchange, they might fit into your room nicely if it has a smaller space for an aquarium.
When deciding on your next aquarium purchase, think about the types of fish you want to keep and the amount of space you have, then buy the largest aquarium that meets your needs.