Hematological parameters of "cachara" Pseudoplatystoma fasciatum Linnaeus, 1766 (Osteichthyes, Pimelodidae), reared in captivity

Abstract

This study was carried out with Pseudoplatystoma fasciatum ("cachara") reared at PDSA - APTA, Pariquera-Açu, São Paulo, Brazil, stocked in eight 200 m² ponds, from January 1999 to February 2001, totalizing 190 fishes (71 males, 99 females and 20 undetermined). The total weight (138.5 to 2,430.0 g) and total length (29.5 to 79.0 cm) were recorded. The sex and the gonadal stages (Juvenile, Resting, Maturation, Final Maturation, Regression) were also identified. Blood was collected to determine the hematocrit (mean value: 28.0 ± 0.6%), hemoglobin level (mean value: 6.4 ± 0.2 g/100 mL) and red blood cell (mean value: 224.0 ± 6.0 x 10⁴/mm³). Mean corpuscular volume (MCV) (mean value: 131.0 ± 2.3 µm³), mean corpuscular hemoglobin (MCH) (mean value: 26.6 ± 1.0 ppg) and mean corpuscular hemoglobin concentration (MCHC) (mean value: 19.8 ± 0.7%) were calculated. There was difference between males and females, and a slight increase in the mean values of the hematological variables with gonadal maturation was registered. Differences among fish according to the several classes of total length were also verified.