Understanding Why Some Aquarium Fish School While Others Don’t

In marine biology, “schooling” refers to thousands of fish species that prefer aggregate company. Schooling fish can often be seen swimming in a group, but they also do many other activities together, such as feeding, exploring, mating, and staying away from predators. This group behavior is purely genetic. Tropical freshwater fish known for their schooling behavior include neon tetras, danios, and some Corydoras. In reef tanks, dartfish and cardinalfish also school together if they have enough space. Fish keepers who are into aquascaping tend to limit their stock to a single school that won’t feed on plants or disturb the substrate. Here’s what you should know about schooling behavior in aquarium fish, brought to you by the knowledgeable staff at Aquatic Warehouse, a leading provider of fish tank supplies.

Schooling Behavior Isn’t Learned

Despite extensive research into schooling fish, scientists don’t have all the answers that relate to this behavior. From an evolutionary point of view, it makes perfect sense for smaller species to swim together as a means of protection, but this doesn’t fully explain why many schools disband in darkness only to regroup in the daytime. What researchers do know with certainty is that fish with limited vision cannot school together, and they also know schooling isn’t something aquatic species can learn. Something else that remains a mystery is why some schools will join others to form a larger group but will later split up.

Solitary Fish Behavior

Solitary fish species include several that are predatory, territorial, or genetically aggressive. In some cases, the genetic predisposition of some fish to live in solitude won’t allow them to live in any kind of community tank. These species include fighting Siamese males (better known as Bettas) as well as quite a few cichlids. Some solitary fish get along with other species as long as they can claim a spot such as a corner of the tank or a space behind rocks. Predatory fish should never be kept in the same tank as schooling species, but they should be fine in habitats with larger fish.

Coordinated Swimming in Schooling Fish

When you stock your tank with colorful schooling fish such as neon tetras, you’ll be mesmerized by their synchronized swimming and feeding. This coordination is enabled not just by the anatomy of the fish but also because this is what they do when they’re juvenile fry. If for any reason a schooling fish loses its vision or other senses, it will no longer be able to join others in a group.

Keeping Schooling Fish Happy in the Aquarium

In the wild, schools of fish may number dozens, hundreds, or thousands of members. Despite decades of behavioral observation, there isn’t an exact science for adding a perfect number of fish to make a school. However, there seems to be a consensus that four to five would be the minimum. The smaller the species, the larger the school should be, but keep in mind that a large school will also increase the bioload in your aquarium.

No matter how many fish you keep in your aquarium, you need to maintain the tank properly to keep its inhabitants happy and healthy. Make sure you have all of the necessary supplies on hand. At Aquatic Warehouse, you can find aquarium controllers, filtration, testing kits, heaters and coolers, and any other supply you need. Order your supplies from our website, come pick them up at our store in Kearny Mesa, or give us a call at 858-467-9297 if you have any questions.