This paper describes the preparation and characterization of collagen films extracted from swim bladders of three species of tropical fishes: Arius parkeri (Gurijuba), Cynoscion acoupa (Pescada Amarela) and Cynoscion leiarchus (Pescada Branca). Collagen was extracted under acidic conditions (CH 3 COOH, 2.5 pH) and precipitated by the addition of NaCl up to 3.0molL −1 . The films were prepared in acrylic containers and dried in a vacuum atmosphere. The collagen films were characterized by hydroxyproline contents, thermal analysis, scanning electron microscopy and impedance spectroscopy. The determined values of 4-hydroxiproline and collagens in the films were: 105.23±4.48 and 873.2; 102.94±4.42 and 854.1; 100.65±4.80 and 835.8mgg −1 for A. parkeri, C. acoupa and C. leiarchus, respectively. Differential scanning calorimetry revealed high denaturation temperature peaks at temperatures ranging from 65.9 to 74.8°C. The micrographs showed no fibrillar organization along the material, but spongy structure, with cavity diameters relatively uniform, at around 2μm. The impedance spectroscopy presented a distributed relaxation process. A. parkeri's films showed piezoelectricity.