Vol.:(0123456789) 1 3 Molecular Biology Reports https://doi.org/10.1007/s11033-019-05027-8 ORIGINAL ARTICLE Immunity augmentation in Botia dario (Hamilton, 1822) through carotenoid: a dietary approach Partha Sarathi Tripathy 1  · Ananya Khatei 1  · Janmejay Parhi 1  · Tanmoy Gon Choudhury 1  · Lopamudra Sahoo 1  · Sagar Chandra Mandal 1 Received: 9 June 2019 / Accepted: 7 August 2019 © Springer Nature B.V. 2019 Abstract The immunity and health status of ornamental fsh is an important aspect, as they are kept in a confned environment and various stressful conditions which lead to depletion of overall colourful appearance and mortality. The carotenoids can act as immunity boosters in captive aquarium system and may be supplemented in the feed as aquarium fsh have no access to natural carotenoids. The study aimed to assess the role of carotenoid on the immunity of B. dario. Marigold petal meal is an important source of carotenoids and used in experimental diets. Four immunogenes namely IL20, TLR9, TRAIL, and Nramp in B. dario were characterized and also studied for their relative expression in the kidney after feeding the fsh with marigold petal meal supplemented diet. The expression pattern of the genes was compared with the fsh of nature. The IL20 and Nramp gene were upregulated signifcantly (p < 0.05) in the fsh of nature as compared to the experimental fsh at the 60th day of feeding carotenoid-rich diet. But the TLR9 and TRAIL gene was upregulated signifcantly (p < 0.05) in experimental fsh as compared to nature. The haematological parameters of fsh after feeding with the experimental enriched diet for 60 days also confrmed the role of carotenoids in immunity. Keywords Carotenoid · Immunity · Gene expression · qPCR · Sequencing Introduction Ornamental fsh production is an important sector world- wide. For India, it is considered to be a boon because of the diversity of ornamental fsh. Aquarium hobby in India is about 70 years old, and overall ornamental fsh trade is about rupees 300 crores with more than 500 outlets for the ornamental fsh market [1]. Botia dario belongs to the family Cobitidae of order Cypriniformes and has a great demand for the aquarium trade in many countries due to its unique band pattern and bright colour [2, 3]. The most important thing regarding the ornamental fsh to attract customers is their vibrant colour and overall look. But ornamental fsh become awful in appearance and dull in the aquarium due to diseases caused by unhealthy water quality and pathogens. The ornamental fsh integument and immune system are often afected by pathogens, mostly bacteria [4] results in dull appearances. Therefore, it is required to boost the immunity of ornamental fsh to mention the health status and its attractive colour. Little has been studied regarding its immunity of ornamental fsh in domesticated condition. The use of diferent prophylactic measures like common salt, potassium permanganate, methylene blue, malachite green, etc. can also cause stressful conditions. Moreover, the methods of application of these prophylactic measures in ornamental fsh are traumatic. Therefore, the inclusion of ingredients as immune boosters in the diet may be helpful for best health management practices of ornamental fsh. The knowledge regarding the dietary inclusion of difer- ent supplements for fsh in triggering their immune system is a critical study. Among these, the dietary addition of carot- enoids can enhance the fsh immune system [5]. But, the natural sources of carotenoids are unavailable to domesti- cated fsh. So, they should be provided with the carotenoid enriched feed from other sources. Carotenoids supplied by marigold petal meal as a supplement in the diet, play an important role in the regulation of skin and muscle colour in fsh [6, 7]. It has been found that carotenoid enhances * Sagar Chandra Mandal scmandal02@gmail.com 1 Department of Fish Genetics and Reproduction, College of Fisheries, Central Agricultural University (Imphal), Lembucherra, Tripura West, Tripura 799210, India