A new towed camera system, known as the Camera-Based Assessment Survey System (C-BASS), is being developed for reef fish stock assessments. This system has the capability of facilitating large-scale quantitative assessments and allows fisheries scientists to enumerate economically important reef fishes in areas such as coral reefs where traditional surveying approaches are not feasible. The system is designed for versatility and simplicity with the goal of being deployable from any vessel equipped with standard oceanographic winches and cables. It is designed to operate in up to 200m depths, and be towed at speeds between 1.5-2 m/s at altitudes of 2-4 m above the sea floor. While being towed, the system stores video from a number of cameras and data from a variety of environmental and system monitoring sensors. The system is powered from the vessel via the cable. A DSL Ethernet based communication link enables the user to view lower resolution video in real time, while full resolution streams are stored on an onboard computer. Coincident environmental data including depth, temperature, salinity, and fluorescence (turbidity and chlorophyll) information as well as tow platform flight characteristics such as altitude above the bottom and tow body attitude are all stored in a MySQL relational database. Presented here is the initial C-BASS research and development phase including sea trial results.