ORIGINAL ARTICLE Hematological parameters of pure and reciprocal crosses of Pangasianodon hypophthalmus (Sauvage, 1878) and Clarias gariepinus (Burchell, 1822) V. T. Okomoda 1 & I. C. C. Koh 2 & A. Hassan 2 & T. Amornsakun 3 & M. S. Shahreza 2,4 Received: 8 November 2017 /Accepted: 5 December 2017 # Springer-Verlag London Ltd., part of Springer Nature 2017 Abstract Comparative study on the hematological parameters of pure and reciprocal crosses of the African and Asian catfish was done to establish a reference range for fingerlings of the novel fish. Blood was collected from Clarias gariepinus (CG), Pangasianodon hypophthalmus (PH), Pangapinus (♀PH × ♂CG), and the two observed morphotypes (Clarias-like and Panga-like) of Clariothalmus (♀CG × ♂PH) obtained from similar breeding history. Result obtained revealed that red blood cell counts and white blood cell counts were significantly lower in Panga-like Clariothalmus (1.08 × 10 6 /mm 3 and 6.99 × 10 3 /mm 3 , respectively) compare to other groups with similar higher counts (between 2.09 × 10 6 /mm 3 and 2.65 × 10 6 /mm 3 ; 13.60 × 10 3 /mm 3 and 17.27 × 10 3 /mm 3 , respectively). However, Pangapinus and pure P. hypophthalmus had significantly higher values of packed cell volume (33.10 and 32.50%, respectively) and hemoglobin content (12.63 and 11.72 g/dL, respectively); similar values were recorded in those fish with Clarias maternal origin (between 25.00–27.80% and 6.67–8.03 g/dL, respectively for PCV and Hb). Calculated values for mean corpuscular volume was higher in Panga-like Clariothalmus (198.8 fL and 80.26 pg, respectively) while mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration values were higher in the Pangapinus and pure P. hypophthalmus (between 48.10–56.98 pg and 38.28–35.96 g/dL, respectively). This result obtained is suggestive that the Panga-like Clariothalmus may have reduced fitness as compared to the other progenies. The baseline values established in this study could serve as a standard for physiological, pathological, and toxicological references in future studies. Keywords African catfish . Asian catfish . Morphotype . PCV . Hb Introduction One of the physiological parameters of utmost importance in animals is the blood (Hesser 1960; Rey Vazquez and Guerrero 2007). It involves the evaluation of the total red blood cell counts (RBC), total white blood cell counts (WBC), hemoglo- bin content (HGB), packed cell volume (PCV), mean corpus- cular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) (Campbell 2004; Mmereole 2009), and many more. Normal hematological parameters vary in different fishes, ages, sexes, and stages of sexual maturity (Golovina 1996; Luskova 1997; Hrubec et al. 2001; Gabriel et al. 2004; Noga 2010). In addi- tion, hematological parameters are closely related to the re- sponse of the animal to the environment; hence, the environ- ment where fishes live exert significant influence on its hema- tological characteristics (Barton 2000; Kori-Siakpere et al. 2005; Gabriel et al. 2004; Solomon and Okomoda 2012). Hematological parameters are often used as an important index for the assessment of the health status of the fish (Ruane et al. 2000; Okomoda et al. 2013). This is because it gives the * M. S. Shahreza shahreza@umt.edu.my 1 Department of Fisheries and Aquaculture, College of Forestry and Fisheries, University of Agriculture, P.M.B 2373 Makurdi, Nigeria 2 School of Fisheries and Aquaculture Sciences, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia 3 Department of Technology and Industries, Faculty of Science and Technology, Prince of Songkla University, Pattani campus, Mueang, Pattani, 94000 Thailand 4 Institute of Tropical Aquaculture, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia Comparative Clinical Pathology https://doi.org/10.1007/s00580-017-2623-z