Nile River

As you marvel over the submerged ruins, you’ll almost certainly glimpse the tell-tale shimmery silver of the tigerfish. This fish is closely related to the South American piranhas and like its namesake, the tiger, it is a powerful predator. Due to its streamlined torpedo-shaped body, the tigerfish is able to move in on its prey swiftly. It grows to be a metre long and with its fang-like teeth, it’s able to eat fish half as long as itself!

They are close cousins of the Southeast Asian arowana (commonly known as the dragon fish) but the difference lies in their lack of barbels. In the wild, it mainly feeds on plankton, though it is capable of eating larger food. We started our African arowana off on bloodworms but have since transitioned them to fish and prawn pieces. Their swim bladder acts as a lung and allows them to breathe in air - a special adaptation to life in oxygen-poor environments.

The modified swim bladder is also found in the bichir (pronounced as “bee-cher’). The 5-18 dorsal finlets along the top of its back are raised when it’s agitated, giving a flag-like appearance.

With its small, flat head and rounded snout, the bichir resembles a salamander. Young bichirs also have feathery external gills similar to those of salamander larvae.

Bichirs are carnivores that emerge at night to feed. They eat anything, including smaller counterparts!

Named for its skin pattern, which resembles that of a giraffe, this fish has scaleless skin. In addition to intake through the gills, it can absorb oxygen directly from the water through its skin.

An opportunistic feeder, it picks plants, invertebrates, even dead fish off the riverbed with its down-turned mouth.

The eggs are guarded by the male parent. He even cares for the eggs and young of another catfish species, which takes advantage of the ready nest.

You might be wondering how we keep all these predatory fish in the same tank without conflict. In the wild, arowanas dwell near the water surface while the tigerfish are mid-column fish. The bichir and the giraffe catfish are both bottom feeders. Each species occupied their own niche. Given their natural tendencies to occupy different layers of the water column, it was not hard to condition these predatory fish to live together in harmony in the same tank!