Does the Site of Blood Collection in Fish Affect Haematological and Blood Biochemical Results?

The values of haematological and selected blood plasma biochemical parameters of juvenile common carp (Cyprinus carpio Linnaeus, 1758) were compared between blood samples taken from caudal vein and heart to evaluate the influence of blood sampling body site on the obtained results in two groups of fish of different blood sampling order: I – first by caudal and then by cardiac puncture, II – first by cardiac and then by caudal puncture. The obtained results revealed statistically significant (p<0.05) differences only in group I where red blood cell (RBC) count was higher in caudal vein blood, while haematocrit (Ht) value, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), total protein (TP) concentration, and magnesium (Mg) level were higher in cardiac blood samples. No statistically significant differences occurred in white blood cell (WBC) count, differential leukocyte count or erythrocyte morphology based on stained blood smears. The obtained results showed that blood sampling body site may affect the results of haematological and plasma biochemical analyses.