Changes in selected physiological parameters of hybrid fish F1(Pangasius krempfi x Pangsaianodon hypophthalmus) fry reared in different salinities

Abstract

The study evaluated the effects of different salinities on hematological parameters of hybrid fish F1 (Pangasius krempfi × Pangasianodon hypophthalmus) fry. The experiment was conducted using a completely randomized design with four salinity treatments 0‰, 6‰, 12‰, and 18‰, each with three replicates. The fish with stocking density of 160 fish/tank was reared in a recirculating aquaculture system (RAS) for one month. Hematological samples were collected 1, 2, 3, and 4 weeks after salinity stabilization, with three fish sampled per tank at each sampling time. The results indicated that both red blood cell (RBC) and white blood cell (WBC) counts increased with increasing salinity and sampling time, particularly during the early stages of the experiment. White blood cell counts exhibited significant differences among treatments throughout the experimental period, with consistently higher values recorded at 18‰ compared to the other salinities. Hematocrit values decreased progressively with increasing salinity and showed statistically significant differences at the second and fourth weeks. Hemoglobin concentration declined with increasing salinity during the first two weeks; however, it became relatively stable and showed no significant differences among treatments during the final two weeks. In contrast, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) exhibited only minor fluctuations and did not differ significantly among salinity, while MCHC showed statistically significant differences at the second and fourth week.