again, the black mudfish expanded its range northwards, eventually surrounding that of the Northland mudfish. The Canterbury mudfish is found across the Canterbury Plains, an alluvial plain formed by large and highly mobile braided rivers. The lack of genetic variation or structuring between populations suggests that these mudfish have been reduced to small founder populations, possibly due to droughts. The subsequent range expansion may have been assisted by mobile braided rivers. References External links New Zealand Mudfishes - a guide. Nick Ling. 2001. Department of Conservation, Wellington, New Zealand. Taxa named by Albert Günther Freshwater fish genera