Hybrids of bleak, Alburnus alburnus, and chub, Leuciscus cephalus in English rivers

The occurrence of hybrids between bleak, Alburnus alburnus , and chub, Leuciscus cephalus is reported from four discrete river systems in England. The hybrids are described and illustrated, and means of identification from the parent species are given. Bleak × chub hybrids appear to be moderately common and on superficial examination resemble the bleak parent species more than the chub.