It is back to school time for most of America’s children. Backpacks, bright yellow buses, and droves of children gathered on street corners to be carted off to fall classes. Our children gather in schools to learn. Meanwhile, around the globe, millions of fish gather in schools for other reasons. Not big brick building schools, but large, synchronized groups – a fascinating behavior known as “schooling.”
What are Schooling Fish?
Schooling is a behavior that benefits fish as individuals and as groups. As the saying goes, “there’s safety in numbers.” Swimming together in large numbers, almost as if a single organism, makes a fish feel more secure. Moving in a massive school reduces the possibility for any single fish in the mass to become prey. Schooling also makes movement more efficient for each fish. Each can move faster and more easiliy as the drag of the water is reduced by the streamlined bodies of surrounding fish in the school. Traveling in large numbers has social benefits as well, it certainly it makes finding a mate and successfully spawning easy if you are surrounded by thousands of potential mates in close proximity.
You’ve probably seen massive schools of sardines, tuna or other fish being marauded and splintered by larger predators on the Discovery Channel or some other nature show. While you probably won’t see these fish available for a home aquarium, there are some options of fish that will exhibit these fascinating behaviors if kept in a large enough aquarium and in large enough groups.
Examples of Saltwater Schooling Fish
One of the best examples of a schooling marine fish is the Green Chromis (Chromis viridis). Green Chromis have beautiful, pastel green-blue coloration. They are non-aggressive and generally hardy in a marine aquarium. This fish has been around the hobby for decades now and is a common sight in retail stores. How many does it take to get these fish to school? At least 6 is the consensus. Unlike other damsels, these fish tend to be mild-mannered and even timid, especially when kept as individuals. Keeping a school of these fish in a tank will promote schooling behavior and make the fish more outgoing.
Other types of marine fish commonly seen and sold as schooling fish are Cardinalfish. While not exactly a schooling fish, a group of these fish will cluster in close proximity to one another on a reef. Why aren’t they schooling? Well, technically they form a shoal, a group of fish (not always the same kind of fish) that stays close, but do not necessarily move and swim together. Either way, these are popular fish the aquarium trade and the shoaling behavior is fun to watch too. Cardinals are generally peaceful and do best in pairs or groups of 5 or more. They do have large mouths, so be wary when keeping them with small shrimp and crabs. Flame Cardinals, the ever popular Banggai Cardinals, PJ Cardinals and Threadfin Cardinals are just a few of the many hardy species that will shoal in your home aquarium.
If you have a freshwater aquarium, the list of schooling fish species is pretty long. Dozens of tetras, barbs, danios, and rasboras are available and new species are being introduced regularly. There are also several other types of schooling fish that you may not see in the average pet store. These colorful and interesting fish can really contribute something special to a home aquarium.
One of the most interesting schooling fish is the African Three-striped Glass Cat, Pareutropius buffei. Collected in the rivers of Cameroon and Nigeria, this is a very peaceful schooling fish with a clear or silvery body, black horizontal stripes and a distinctively blunt nose. Constantly buzzing around in search of food, a group of these 3 inch fish will go into a veritable feeding frenzy once food is located. This species is one of the best scavengers available for the freshwater community aquarium. A single specimen will likely hide and may refuse to eat, so make sure to keep several of these fish (groups of at least 6 individuals) to make them feel secure. Open swimming space is a must, but some plants for cover will be appreciated. They can be housed with community fish including Rosy Barbs, Cherry Barbs, Serpae Tetras, and other similarly active medium-sized species.
Staying with the “something different” theme, cichlid enthusiasts may want to try fish belonging to the genera Cyprichromis and Paracyprichromis. These fish are available from time to time (though sometimes at a high cost) and they are quite different from your typical cichlid, in build and in behavior. Both Cyprichromis and Paracyprichromis are sardine-like cichlids that inhabit the open waters of Lake Tanganyika. They can be found in very large schools, feeding on zooplankton. Cyprichromis are the larger of the two genera, with one species (Cyprichromis zonatus) reaching almost 6 inches. Cyprichromis leptosoma is probably the most common species in the trade, with several regional variants available to hobbyists. Males often display vibrant blue and yellow color and will often “light up” when next to another male for an impressive display.
There are two species of the smaller Paracyprichromis currently described, with only one seen readily in the hobby. Paracyprichromis nigripinnis is a charming little torpedo-shaped fish that that grows to about 3.5 to 4 inches. Both males and females are golden brown with blue stripes. Mature, dominant males have intense neon blue coloration in those stripes and through the fins. Like their bigger cousins, Paracyprichromis are found in open water columns in Lake Tanganyika.
Both Cyprichromis and Paracyprichromis will fair best in species tanks or Tanganyikan community tanks with at least 6 or 8 individuals in the school. If you can manage more, it always helps to keep them calm make them feel secure, but the bare minimum should always be 6. Adding some ornamentation to the tank is acceptable, but make sure that you leave plenty of open swimming space.
Hit the Books!
With so many choices out there for schooling fish, don’t be shy about doing some research and checking out some that are a little less common! Whether it is a strange catfish or a new type of rainbowfish or one of the cichlids mentioned above, schooling behavior definitely adds life and energy to your aquarium. You will see interactions between fish that you would never see otherwise!