What Is The Lateral Line System?

UNDERSTANDING THE LATERALIS SYSTEM

The Asian Arowana (Scleropages Formosus) – also known as the dragon fish – inhabits the blackwater rivers of Southeast Asia, where waters have distinct clarity. Nonetheless, the clarity quickly disappears after heavy downpours due to the sediments being washed down from surrounding forest. Sometimes, this murkiness may persist for a few days before restoring to its previous clarity.

How then do these Asian Arowanas find their way around the river during these periods of low visibility? The secret lies within the dots along the sides of these Asian Arowanas.

Revealing the Secret

The lateral line system (lateralis system) is the secret to its ability in finding a way around waters with low visibility. In fact, this system is present in all fishes and can also be found in most amphibian larvae, and even some adult amphibians. The lateral line is a line of scales which stands out from the rest of the scales, running from its mouth, along its body to its tail. These scales are rather visible to the naked eye as shown in the below diagram.

This sensory system is made up of modified scales, with its barbels, works like the sonar of a submarine which allows the Asian Arowanas to avoid collision onto solid objects and detect nearby predators and preys, even before seeing them. This lateralis system is vital to domesticated Asian Arowanas, as it prevents them from bumping into the walls of the glass tanks, which they are able to sense but not see.

Schooling fishes also depend on it to swim in close proximity of each other within the school without collision, even when the school makes sudden change in direction or when fleeing from its predators.

Other ornamental fishes like the goldfish, discus and blood parrot possesses the lateralis system too. Can you spot them?

Lateral Line Erosion

Like all fishes, the Asian Arowanas have a high dependency on lateralis system, therefore it is important for hobbyists to prevent them from developing the Lateral Line Erosion (LLE) – also referred to as Lateral Line Disease (LLD) or Head and Lateral Line Erosion (HLLE). This is rather common among Arowanas especially golden ones, thus the upkeep of its living environment should be maintained to prevent it. It is recommended for hobbyists to conduct regular water change, provide proper filtration, as well as providing the required nutrition to ensure that their aquatic friends stay healthy.