Haematology, morphology and blood cells characteristics of male and female Siamese fighting fish (Betta splendens)

The aim of the present study was to obtain baseline data on blood cell size, morphology and haematological parameters in Siamese fighting fish (Betta splendens) since there is limited information in the published literature. Blood samples from the caudal vein of apparently healthy Siamese fighting fish (male: n = 40 and female: n = 36) were collected. Haematological values of the blood samples were determined using standard techniques. The morphological features of blood cells were described according to observations made by light microscopy. The various types of blood cells measurement were carried out with the help of a stage and an ocular micrometre at a magnification of ×1,000. Erythrocytes, thrombocytes and four types of leucocytes: lymphocytes, monocytes, heterophils and eosinophils, were distinguished and characterised. The average size of the erythrocyte cell and nucleus was 97.33 and 16.28 μm², respectively. Results showed a positive correlation between erythrocyte size and nucleus size for Siamese fighting fish (r = 0.470, p < 0.01). We also found sex-dependent differences for total white blood cell count, lymphocytes and heterophils in Siamese fighting fish (p < 0.05). Statistical analysis revealed that differences in other haematological parameters and blood cell morphology, between male and female fish were not statistically significant (p > 0.05).