The Fish chapter in Handbook of Biodiversity Survey Methods: Survey, Evaluation and Monitoring provides useful information on the survey and monitoring of fish species.
This is part of our Good Practice Guidance for Fish, produced by Vaughan Lewis, Steve Coates and Kerry Sims.
Reference: Giles N, Sands R and Fasham M (2005). Fish in: Hill D, Fasham M, Tucker P, Shewry M and Shaw P (eds) Handbook of Biodiversity Methods: Survey, Evaluation and Monitoring, 368-386. Cambridge University Press, Cambridge.