Rivers receiving acid mine drainage (AMD) are frequently depauperate in fish and impacts may extend long distances downstream. AMD inputs may form chemical barriers for migratory species and isolate fish in unimpacted headwaters. We investigated the response of a diadromous fish, kōaro ( Galaxias brevipinnis ), to remediation of an AMD tributary in a 5th order river in New Zealand. A 2005 survey indicated limited recruitment o...