Collagen is the most abundant protein found in animal body and widely used for biomedical and pharmaceutical applications. However, its applicability is severely limited due to high cost. Fish processing waste, which otherwise cause serious environmental pollution, is a promising cost effective collagen source. In the present study, collagen was isolated from scales of Labeo rohita (Rohu) and Catla catla (Catla). It is first time that these species are used as sources of collagen. Thermo-gravimetric analysis (TGA) revealed maximum demineralization achieved after 48 h of EDTA treatment of intact scale. The isolated protein was confirmed as collagen by different physico-chemical techniques like FTIR, SDS-PAGE, and CD. Further amino acid analysis corroborates isolation of type I collagen. A major characteristic of obtained collagen was found to have denaturation temperature (T(d)) of 36.5 degrees C, which is promising as an advantage for biomedical application due to closeness in T(d) to mammalian collagen. (C) 2010 Elsevier Ltd. All rights reserved.