Enhancement of reproductive performances of Gangetic leaffish, Nandus nandus through up regulation of serum Ca 2+ concentration, improved morphological alteration of liver and ovary with dietary polyunsaturated fatty acids A. H. M. M. Reza • S. F. Rakhi • M. S. Hossen • K. Takahashi • Z. Hossain Received: 7 May 2012 / Accepted: 17 October 2012 / Published online: 30 October 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract Incorporation of polyunsaturated fatty acids (PUFAs) as biofunctional compounds with feed is an effective way for gonadal maturation without any hazardous effects on animal health, and thus it is possible to save the vulnerable species from the danger of extinction. In the present study sperm quality, level of Ca 2? concentration in serum, histological structure of the liver and developmental stages of ovary of an endangered fish species, Nandus nandus were investi- gated for the confirmation of the positive effects of PUFAs in reproduction and gonadal maturation. Fishes were collected from Brahmaputra River, Mymensingh, Bangladesh. Treated group was fed 1 % squid extracted phospholipid supplemented diet that was mixed with silver carp fish muscle where as controlled group was fed the same except phospholipid. For histology of liver and gonads, samples were dehydrated, cleaned and infiltrated, embedded in paraffin wax and sectioned. After that, the samples were stained with hematoxylin and eosin. The photomicrographs of the stained samples were taken by using light microscope. In comparison with the control group, treated group exhibited higher gonadal maturation which resulted in spontaneous spawning. Treated female demonstrated advanced gonadal developmental stages in comparison with the controlled female during different months. During spawning season, lipid granules and normal morpho- logical alteration were observed in case of treated fish liver, whereas less lipid granules with more histological alteration of liver were observed in control group. Serum Ca 2? concentration in treated female was found significantly higher (P \ 0.01) in contrast to the con- trolled female during the breeding season which was an indicator of the augment of estrogen secretion during ovarian maturation. Better sperm quality, early matura- tion of oocytes, less histological alteration of liver hepatocytes and spontaneous spawning performances of PUFA-treated fish were as a result of the efficiency of PUFAs in enhancing maturation. The experiment suggests that supplementation of dietary PUFAs improve the spawning performances of fish. Keywords Ca 2? concentration Á Gonadal maturation Á Nandus nandus Á Polyunsaturated fatty acids Á Spontaneous spawning Introduction Reproductive physiology of fish is synchronized with environmental, social and nutritional factors. Due to the A. H. M. M. Reza Á S. F. Rakhi Á M. S. Hossen Á Z. Hossain (&) Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh e-mail: zakirh1000@yahoo.com URL: www.bau.edu.bd K. Takahashi Faculty of Fisheries, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan 123 Fish Physiol Biochem (2013) 39:779–791 DOI 10.1007/s10695-012-9740-z