How to identify african tigerfish

Safety

Look at this first

Diagnostic — settles it on its own

Each of these settles the identification on its own. If one is clear, you have your answer.

• Fangs that remain visible with the mouth shut

  Look at the jaw line of a closed mouth from the side. The upper and lower teeth pass outside each other rather than meeting inside, so they show along the outside of the lip as a row of points. This is a structural arrangement rather than a colour or a shade: it is present on every individual at every size, it survives death and poor light, and it is visible in almost any photograph that shows the head. It is the character to check first and it settles the genus on its own.

Supporting — use with other characters

Real characters that are not conclusive by themselves. Use two or three together.

• Dark horizontal stripes along a bright silver flank

  Look along the side of the fish for a set of narrow dark lines running head to tail rather than up and down. They are distinct and evenly spaced on a healthy fish and they are the reason for the name. Treat this as confirmation of the species within the genus rather than as the primary test: the stripes fade on a dead or stressed fish, they vary in strength between individuals and populations, and the goliath tigerfish of the Congo carries a much more uniform silver flank with the striping far less strongly marked.

• How big the fish is, and which river it came from

  Ordinary rod-caught fish run one to three kilos and a very good one is six to ten, with a maximum published weight around 28 kg. A very large Hydrocynus from the Congo basin or Lake Tanganyika is much more likely to be the goliath tigerfish, which reaches weights this species does not approach. Range is supporting evidence and never an identification on its own — this species is spread across an enormous list of African systems from the Niger and the Nile to the Zambezi and the Okavango, and the two overlap in places.

• A streamlined body with a deeply forked tail

  Seen side on the fish is laterally compressed and built along its length rather than deep, and the tail is deeply forked. That is the profile of a pursuit predator that runs prey down in open water rather than ambushing from cover, and it fits everything else about the animal. It will not separate this fish from its congeners, all of which share the build, but it does rule out the deep-bodied and blunt-tailed predators of the same water.

Suggestive only — varies with condition

Hints only. These vary with condition, season, water and how long the fish has been out of it, and a fish that contradicts them is still the same species.

• Orange to red caudal and anal fins

  The tail and the fin beneath the rear of the body carry a warm orange or red wash, strongest on a fresh fish. It is a genuine mark and it is worth noticing, but it is a colour on a fish that loses colour quickly out of water and in a photograph taken in strong African light. Rank it below the teeth and below the stripes, and never let it settle an identification against a character that contradicts it.

What it gets confused with

• Goliath tigerfish in the Congo basin and Lake Tanganyika, which is the same genus at a much larger size with a more uniform silver flank and far weaker striping. A very large Hydrocynus from those waters is very unlikely to be this species.
• Other Hydrocynus species across the African systems, several of which are separated on stripe pattern and proportion rather than on anything obvious, and which a photograph frequently cannot settle.
• Large characins of the same rivers at a glance and at a distance, though none of them carries teeth outside a closed mouth and the first look resolves it immediately.

Where this stops working

The full record

This page covers identification only. The African tigerfish record covers behaviour, lifecycle, distribution, handling and the sources behind all of it.