Selecting Fish for a Freshwater Community Aquarium
A freshwater community aquarium contains multiple different species of fish that must be compatible. Depending on the fish species they will have a preference to swim and live in the topwater, midwater or bottom of the aquarium. When selecting your fish for your aquarium you want to select fish with these three areas in mind to assure every level of your aquarium is used.
You will also want to understand which fish do better in schools. Seeing fish swim in unison through an aquarium adds beauty and excitement to any aquarium. Many fish such as cardinal tetras and white cloud minnows are fish that prefer to be in a grouping and will swim as a school. A school of fish in an aquarium should always be at least 5 or more of the same species. Examples of excellent schooling fish for a community aquarium include: Rummynose Tetras, Cherry Barbs, Harlequin Rasboras, Zebra Danios, Congo Tetras, Glowlight Tetras, Bloodfin Tetras, Pigmy Corydoras, Denison Barbs, Archerfish, Cardinal Tetras, and White Cloud Minnows just to name few.
The maximum size of your fish is another consideration. The size of your aquarium is certainly a major influence on what you should and should not keep. If you have an aquarium that is relatively small say 10 to 20 gallons (40 to 80 liters) then you would not want to keep a fish that will grow to a length of 12 inches (30 cm). Fish will continue to grow throughout their entire life. Some species are very peaceful when they are small but as they grow, they can become aggressive and solidary as adults. Fish that grow large and become aggressive are not good choices for a community aquarium.
You should plan and develop a list on the amount and type of fish you want to have in your aquarium. Do not just go buy fish based on their colo(u)r or personality at the fish store without knowing what they need in terms of volume of water and how big they will become. Without a clear plan about what fish to add to your aquarium, the fish you buy may not be compatible.
Calculating the number of fish your aquarium can hold is also important. You will need to think about the adult size of the fish you put in your aquarium. Many factors determine how many fish your aquarium can hold beyond just the size of the aquarium. The type of fish will determine this as well. A wide body fish such as a goldfish requires much more space than a slim body such as a Rummynose Tetra. Three-inch (8 cm) body of a goldfish produces a lot more waste than a three-inch (8 cm) body of a Tetra. The efficiency of your aquarium filter will also be a factor for how many fish are appropriate for your aquarium. A 10-gallon (40-liter) aquarium can easily hold 6 to 8 slim body fish but could not maintain 6 to 8 goldfish.
Most tetras, barbs, gouramies, and livebearers are ideal for a community aquarium. Be sure to do your research to choose the best fish types for your aquarium. Other choices include bottom feeders such as Corydoras and Otocinclus catfish. Then there are fish such as bettas, who make ideal community aquarium residents, but male bettas are intolerant of other male bettas, so only one male betta per aquarium.
So as an example, if you have a 10 gallon (40 Liter) tropical aquarium, some fish types to look at are: Platys (any variety), Neon Tetras, Cardinal Tetras, Bloodfin Tetras, Head-and-Tail Tetras, Blind Cave Tetras, Flame Tetras, Cherry Barbs, Gold Barbs, Rosy Barbs, Checker Barbs, Zebra Danios, Pearl Danios, Bettas (1 male/aquarium), Dwarf Gouramies, White Cloud Minnows, Green Corys, Peppered Corys, and Octocinclus. This is by no means a complete list, but it is hard to go wrong with any of these fish.
If you have a 20 gallon (80 Liter) tropical aquarium you can also consider the following as well: Swordtails (any variety), Snakeskin Gouramies, Giant Danios, Congo Tetras, Rainbowfish, Red-eyed Tetras, Scissortail Rasboras. Again, these are just examples for your consideration in making your list for your tropical aquarium.
The final decision on what type of fish to eventually put into your aquarium is purely a matter of preference. A community aquarium exists when several species of fish are maintained together in an aquarium. Mixing multiple species together provides an interesting visual and is exciting to watch them all swim together.