Growth curve estimation by lepidology, and mean body total length at first maturation of Schizodon nasutus Kner, 1859 (Osteichthyes, Anostomidae)in Ibitinga Reservoir (21º46’S í 48º59’W), São Paulo State, Brazil

Abstract

The growth curve according to von Bertalanffy equation and referred to Schizodon nasutus Kner, 1859 was determined through Werder and Soares (1984) method, which employs the counting of age rings in scales. A total of 50 specimens caught from July 1989 to June 1990 were analyzed. The scales located on the area benneath pectoral fin were the best for lecture. The relationships between age and body total length were found to be : 1st year - 96.40 mm ; 2nd year - 149.29 mm; 3rd year - 189.21 mm; 4th year - 224.89 mm; 5th year - 264.78 mm; 6th year 277.95 mm in females; 1st year - 92.43 mm; 2nd year - 148.65 mm; 3rd year - 181.61 mm; 4th year - 215.69 mm; 5th year - 238.92 mm, in males. Mean body total length during first gonadal maturation was found to be 160.5 mm in females and 140.5 mm in males, when fishes are 2 year old.