How sex and temperature influence brooder Giant Kokopu cellular and biochemistry haematology

Haematological and metabolic profiles of brooder giant kokopu, Galaxias argenteus (Gmelin 1789) based on sex and temperature

This study assessed the selected peripheral blood haematological parameters and metabolite profiles linked to liver, serum and muscle samples in 3-year-old male (weight = 131.19 ± 29.24 g; total length = 21.33 ± 1.20 cm; n = 5) and female (122.96 ± 27.04 g; total length = 21.09 ± 1.09 cm; n = 5) giant kokopu (Galaxias argenteus) broodstock cultured at 12°C and 16°C. Temperature and sex did not influence haematocrit values or counts of total blood cells, erythrocytes and leucocytes. However, fish reared at 16°C had higher thrombocyte counts, whereas those kept at 12°C exhibited the highest proportion of lymphocytes. At the metabolic level, sex was the main factor that influenced metabolite levels across tissues, with particularly higher amino acid metabolites in liver of females. Changes linked to the interaction between temperature and sex showed significant differences in fatty acid profiles of liver, and in amino acids in muscle and serum samples. Males kept at 16°C exhibited decreased levels of myristic acid and nonadecanoic acid linked to homeoviscous adaptation. In females, levels for energy metabolites including tyrosine and aspartic acid (in muscle), and alanine (in serum) were disturbed at 16°C. The study provides insights into preliminary haematological and metabolic effects associated with sex and temperature in galaxiids.