Do Males and Females of Colossoma macropomum (Cuvier, 1818) Differ in Hematology and Blood Biochemistry During Sexual Maturation in a Recirculating Aquaculture System?

Hematological and blood biochemical parameters are useful tools for monitoring fish physiological status; however, information on their variation between sexes during reproductive development remains limited for Colossoma macropomum. This study evaluated the hematological and blood biochemical profiles of male and female C. macropomum during growth and first sexual maturation under controlled conditions in a recirculating aquaculture system. Fish were sampled at seven ages from 590 to 1080 days after hatching (DAH). Hematocrit, total plasma protein, hemoglobin, leukocytes, erythrocytes, glucose, cholesterol, and triglycerides were evaluated, and reproductive development was assessed through macroscopic and histological examination of the gonads. Age significantly affected hematocrit, leukocytes, erythrocytes, glucose, triglycerides, cholesterol, and total plasma protein, whereas hemoglobin remained unchanged. Sex significantly affected only glucose, with females showing higher concentrations than males across ages. A significant sex × age interaction was detected only for total plasma protein, with higher concentrations in females than males at 1080 DAH. These findings indicate that developmental progression associated with age is a major source of variation in blood profiles, whereas sex-related effects are limited and parameter-specific. The results provide baseline physiological information for monitoring C. macropomum broodstock under controlled conditions.