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What to Consider Before Buying New Aquarium Fish


I enjoy aquariums, and I have a pet Clown Knife, among other fish. I also like sharing tips with beginners.

Get some ideas of things to think about before you buy new fish for your aquarium.

Get some ideas of things to think about before you buy new fish for your aquarium.

A sparkling aquarium with beautiful fish can be a wonderful addition to any home. Whether you have owned aquarium fish before or are setting up a fish tank for the first time, there are many things to consider when buying new fish. By following these tips, you will minimize any potential headaches in the long run, freeing up more time and energy to simply enjoy your fish tank.

  • Freshwater or Saltwater?
  • Fish Size and Tank Size
  • Community Fish
  • Food and Care

Freshwater or Saltwater Fish?

You have the choice of setting up either a freshwater aquarium or a saltwater one, but be warned, saltwater aquariums require considerably more maintenance to keep the water just right. Furthermore, saltwater fish can be much more expensive and delicate than their freshwater counterparts.

If you enjoy embracing challenge, then of course you might be tempted by the beauty of the brighter and more exotic-looking saltwater fish, but if you are a beginner, then a freshwater aquarium is certainly recommended. If you think you might get bored with the options for freshwater tropical fish, locate an aquarium-only pet store in your area. They will have much more variety than a large generic chain store like PetSmart.


Fish Size and Tank Size

The size of your tank is a very important consideration when picking out new fish. You want them to have room to swim around, and the smaller the fish, the easier it will be to keep the aquarium clean. Smaller fish will also be cheaper and easier to manage for beginners. Also, some fish will require more room than others, so if you are not sure, be sure to consult with the aquarium store staff when you are deciding.

Lastly, be aware of the growth and maximum size of the fish you are getting. While the size of the tank usually limits the growth of the fish (it causes them to produce hormones that limits growth), it does not always. Columbian Shark Catfish, for example, will grow until they are simply unmanageable in a smaller tank. Furthermore, if you get a fish with a very large maximum size, but it stays small in a smaller tank, the stress of the hormones that keep the fish smaller will still shorten its life span.

Community Fish

When putting together a community of fish, you want to be sure to select ones that will get along. Avoid aggressive species unless you are only getting that species, and get them all at once. Once fish communities are established, introducing new fish can sometimes cause fish fights, particularly with the more aggressive, dominance-oriented species.

Certain species of fish will only get along with their own kind, or sometimes not even their own kind, so do research and plan the fish you are looking for rather than buying them spontaneously. Also, avoid putting very small fish together with very large fish or the smaller fish will likely become dinner for the latter.

Clown Knife


Fish Food and Care

Before committing to new fish, be aware of the food and care requirements of the species that interest you. Some, such as the Clown Knife, require special food (live food or frozen bloodworms work best) and are not ideal for beginners or those who want easier care. Others thrive best with a specific PH balance in the water—more acidic or more alkaline—although most fish will get used to the more alkaline water of a well-managed tank.

If you want low-maintenance, look for less “dirty” fish that won’t leave as much fish-waste. While goldfish may be tempting for their hardiness, they also tend to produce a lot of fish-waste. If you get an algae-eater (plecostomus), which is a good way to keep your aquarium clean, they will likely require additional algae wafers to supplement the algae they can eat in the tank (unless the fish is small and your tank produces a lot of algae).

Lastly, be aware that many fish are more delicate than others. If you are a beginner stay away from these; discus fish may be beautiful, but they are expensive and require expert care to keep them healthy.

Tank Size


Norma Lawrence from California on September 21, 2016:

Fabulous article. Such great information. The pictures are beautiful. Thanks