Often, when a community aquarium is mentioned, the normal frame of mind is a freshwater community of small, peaceful fish happily cavorting among a lush green landscape of aquatic plants. However, there are both saltwater and freshwater community aquariums.
Once the aquarium has been set up and you have chosen to make it a community tank, some time and care should be taken to research your fish. It is important that not only the temperament of the fish be identified to see if the fish will play well with others, but also to examine if there are any special requirements the fish has that your aquarium does not meet. For example, if you are interested in a freshwater or saltwater Goby, many of them like to burrow in sand. If your aquarium is not set up with sand on the bottom, the substrate either needs to be changed or the Goby needs to be skipped. Something else to consider when choosing fish is whether the fish prefer to be in a group, a pair, or if it would rather be the only one of its kind. A male freshwater swordtail, for example, will do fine alone, but would prefer to be with 2 or 3 females of its own kind. A Neon Tetra will be happiest in schools of 5 or more; purchasing only 2 or 3 may not be as beneficial to the fish as adding a larger school to the aquarium. In saltwater community tanks, if two clownfish are put into an aquarium together when they are small, one will become female and the other will become male, which brings out interesting behavior as the fish mature.
Another thing to research when choosing your community fish is the behavior of the fish when swimming, especially noting if it tends to swim much at all. This will help to make your aquarium more interesting by allowing you to choose different fish for each “level” of your aquarium. Choosing some fish that tend to swim on top, some that are mid-level dwellers, and some bottom dwelling fish will add interest to all areas of your aquarium. Choosing all Tetras or all livebearers for a freshwater aquarium leaves out the valuable bottom space where a group of Corydoras catfish would look great. A Gourami would also make a great visual impact to the top level of the aquarium. Planning fish for an aquarium is a little bit like landscaping outside of a home, in that you want to add visual depth by planning on multiple levels. This is often referred to as “fishscaping.”
A third item to consider when researching your fish is the water condition and environment are the fish most comfortable in. Some fish prefer warmer or cooler water, a certain PH balance, or a certain amount of open swimming space or heavy cover to hide in. The Catalina Goby, for example, would not make a great tank mate for many other community fish, as it prefers to live in a cool water aquarium. Putting a Catalina Goby in a regular tank would subject it to overly warm water, which will drastically decrease its lifespan.
Last but not least, consider if you are able to meet the dietary needs and feeding behavior of the fish you plan to keep. For example, if you are planning to keep a saltwater community aquarium based on seahorses and pipefish, you should be prepared to have a steady supply of live brine shrimp and copepods available until the fish can be converted to a frozen food alternative. Those are very specialized fish, though. Most community fish, such as freshwater Swords, Tetras, and Gouramis, will eat the usual flake and pellet foods without anything fancy and do just fine. Most saltwater community fish will also handle standard commercially prepared food and do just fine, as well, but saltwater fish tend to have a higher chance of needing specialized diets.
When the “fishscaping” technique is used to create depth and interest in the aquarium, and the factors of environment and dietary requirements are considered, your community of fish will be happier. This will allow the fish to live long lives and provide hours of relaxation and enjoyment for everyone who watches them.