Roach is the commonly used name for a European sport fish. This fish is not found in North America and the name roach is used to refer to certain species of minnow, sunfish and Rudd.
FACT 1: The roach Rutilus rutilus is found in lakes and slow moving rivers of Europe. It is a high backed yellowish green fish with red eyes. It can vary from 15 to 40cm in length. Some roaches can weigh up to 2 kg.
FACT 2: The European roach live in small schools. They are opportunistic feeders and live on aquatic plants, small animals and insects that drift on the surface of the water. The flesh of the roach is sometimes consumed, but they are mostly sport fish. They are also used as bait by anglers.
FACT 3: The roach is a sub- tropical fish endemic to the north eastern regions of Europe and Northern Asia. The roach thrives in waters with a temperature range of 100 to 200C. Roach are not found naturally in the Iberian Peninsula and Italy. Their habitat range has been widely increased by anglers either by accident or design. Expanding populations of roach are now found in Australia, Portugal, UK, Australia, Ireland, Kazakhstan, Cyprus and Italy. They were introduced to Madagascar, but do not thrive there.
FACT 4: In 1889, an Irish angler accidently introduced roach into the River Blackwater in Cork. The fish has spread throughout Ireland and are plentiful wherever they are found. The introduction of the roach has had a deleterious effect on the Rudd populations, which are no longer found in many parts of Ireland. Roach also compete with other species for food. The reduction in the populations of tufted duck in waters where the roach thrive can be linked to competition for food. The roach is now being considered a threat to native eco systems and efforts are being made to control the populations.
FACT 5: The Lavinia symmetricus is known as the Redhills Roach. It is found in a few small streams in the Red Hill area of California. They are tiny stout little fish with deeply forked tails. Their colour ranges from shadowy grey to steel blue. They are omnivores and live on algae, crustaceans and drifting insects.
FACT 6: The Red Hills Roach does not grow bigger than 120mm, but these tiny little fish lay about 2000 eggs in one spawning season. Spawning season takes place between March and July, when the water temperature exceeds 160 C. Male and female fish can be differentiated by the ratio of pectoral fin to body length.
FACT 7: In 2014 California suffered severe drought conditions. The loss of aquatic habitat led to severe depletion of the roach populations. They are now listed as a Species of Special Concern in the State of California.
FACT 8: The Californian Roach – Hesperoleucus symmetricus –is about 11 cm long. It is found in most of California, either as its natural habitat or through bait-bucket introduction.
FACT 9: The Californian Roach can survive where most other fish cannot because of its small size and tolerance of low levels of oxygen. It can also survive high temperatures.
FACT 10: Despite being adapted to survive, the populations are declining and in some cases disappearing from their native ranges. This is probably due to the introduction of the green sunfish in to their native waters. The green sunfish preys on the roach.