Roach feed on both animal matter and vegetation, principal foods being insect larvae, small molluscs and waterweed. They are tolerant of poor water conditions, even polluted water low in oxygen. The fish spawn from April to June in shallow water and attach their eggs – as many as 100,000 – to stones and plants. These hatch within four to ten days, the fish larvae remaining attached to the vegetation until they have exhausted their yolk sacs. The young roach remain in shallow water and grow slowly, the males reaching maturity at two years, the females at three.
Although used as a source of cheap food in some eastern parts of its range, the roach is known primarily as a sport-fish. Its sheer abundance and ability to tolerate poor quality water means that it one of the most common fish caught by anglers. The fish’s natural predators include pike, eels and other large carnivorous fish, herons, osprey and aquatic mammals such as mink and otter.