The roach is native to most of Europe and eastwards into Asia, but it not native to Ireland. The roach is, in fact, one of our most invasive freshwater fish and has been largely blamed for the decline in some native species and other introduced species. Roach have a number of characteristics that make them very competitive:
- They are far are more tolerant of nutrient enrichment and poorer water quality than native salmonids.
- They have a broad diet and will feed on plants, plankton, invertebrates and algae.
- They are fertile and reproduce prolifically in suitable habitat.
Roach are silver in colour with characteristically red fins, red eyes and a forwards facing mouth. They typically form shoals and feed close to the bottom in lakes, canals and deeper, slower-flowing rivers. Although relatively slow growing, roach are long-lived, and many individuals survive for more than 10 years and reach up to 2kg in weight. Roach spawn in shallow areas with dense aquatic vegetation in the late spring or early summer. In Ireland, roach can interbreed with other closely related species from the Cyprinidae family of fishes and forms hybrids with bream and, occasionally, with rudd.
Roach were first documented in Ireland in 1889 on the Munster Blackwater after their introduction as live bait, along with dace, by anglers visiting from England. By the late 1940s, they became established and even widespread in some places in the catchment. Between the 1960s and 1980s, their spread to new locations became rapid, probably as live bait and food for pike. Today, there are few, if any, major river systems that remain uncolonised by roach. Roach are one of the most important fish species for coarse anglers in Ireland today.