Scientific name:Perca fluviatilis
Perch live in schools, usually in the top 50 metres of water, and often mix with other species of fish. Redfin perch are a popular sport fish with some anglers because of their fighting qualities and taste. However, they are also voracious predators of other fish and invertebrates. They can destroy recreational fisheries in enclosed waters by stunting the growth of other fish species or eliminating them.
Where does this species come from?Eurasia
What is its invasive status in South Africa?Category 1b (National Parks, Provincial and Forestry Reserves; Category 3 (all other discrete catchment systems in which they occur).
Where in South Africa is it a problem?Western Cape and Florida Lake in Gauteng.
How does it spread?The sticky, ribbon-like structure of the eggs is responsible for the spread of this fish to most bodies of permanent water; the eggs are transferred to other environments when they become entangled around the legs of wading birds.
Why is it a problem?As predators upon zooplankton, macroinvertebrates and fish, perch have the potential to significantly alter native freshwater communities and can devastate native fish populations by carrying the Epizootic Haematopoietic Necrosis Virus (EHNV).
What does it look like?Description: The perch is a distinctive fish with a deep greenish body marked with dark vertical bands and the dorsal fin is stiffened with spines. The tail and anal fins are orange and the gill covers are tipped with a sharp spine. The erect dorsal fin has a noticeable black spot at the rear. They can weigh up to 4kg and reach up to 25cm in length. Habitat: This species prefers slow-moving rivers, deep lakes and ponds, where it stays close to patches of vegetation and submerged objects. Perch require well-oxygenated water to survive. Breeding: Spawning takes place in April, and the very sticky eggs are produced in bands. Females twine these bands around submerged vegetation or between rocks, and the males follow them and fertilise the eggs. The young fish hatch after about three weeks and remain amongst the egg bands until the yolk sac is exhausted. They then venture into more open water and feed on planktonic animals. As they grow, they begin to form shoals close to the bank. Males mature when they reach 7-8cm in length, females when they are 10cm.