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.