Research Article EXPLORING THE POTENTIAL OF VELVET BEAN, MUCUNA PRURIENS (L) SEED ON GROWTH AND GONADAL DEVELOPMENT OF MONO-SEX COMMON MOLY POECILIA SPHENOPS (VALENCIENNES, 1846) INTRODUCTION Successful reproduction plays a key role in ornamental fish culture, as the process increases population and thus profitability. However, uncontrolled reproduction typically causes overcrowding, a decline in growth, and a high percentage of fish become stunted reducing profitability [1]. Monosex culture is the most widely practised and cost-efficient means of limiting unregulated reproduction. It is labour-intensive and involves hand-to-hand separation of sexes, environmental changes, hybridization, sex reversal and genetic engineering techniques such as androgenesis, Suhas Lingadalli Shivanna 1 , Krishnakumar Velayudhannair 1* , Ashitha Raghu 1 , Rakesh Bhaskar 1 , Divya Kandathil Radhakrishnan 2 , John Paul Arockiasamy 3 , Praveen Nagella 1 Received 31 August 2023, revised 19 June 2024 ABSTRACT: Mucuna pruriens, a rich source of L-dihydroxyphenylalanine, commonly known as L-DOPA and a precursor to dopamine, holds potential as a natural nutritional supplement. This study aimed to delve into the impact of incorporating M. pruriens seed powder (MpSP) into the feed on growth parameters and gonadal development of mono-sex common molly (Poecilia sphenops). The fish population was divided into three experimental groups, such as G1, G2, and G3, and a control group (C), each comprising 20 individuals. Over 45 days, the experimental groups were nourished with a commercial diet bolstered by MpSP in different concentrations (5, 7 and 10g/kg of feed, respectively). In contrast, the control group was provided with a regular diet devoid of the supplement. At the end of the experiment, MpSP demonstrated significant modulation (p<0.05) of growth performance metrics, including specific growth rate (SGR), length gain rate (LGR), body mass gain (BMG), and feed conversion ratio (FCR). Impressively, even the lower concentration of MpSP (5g/kg diet) yielded substantial increments in sperm count (p <0.05) and gonadosomatic index (GSI). These findings were corroborated by histological changes that reflected enhanced testicular development, consistently outperforming the control group. These outcomes collectively suggest the potential of velvet bean seed powder as a feasible, natural, and cost- effective dietary supplement for enhancing growth and testicular development in mono-sex P. sphenops. Keywords: Poecilia sphenops, Velvet bean, Gonadal development, Growth performance, Diet supplementation. 1 Department of Life Sciences, Christ University, Hosur Road, Dharmaram College Post, Bengaluru - 560029, Karnataka, India. 2 Department of Zoology, Bharathiar University, Coimbatore, Tamilnadu, India. 3 Department of Zoology, St. Josephs's University, 36 Lalbagh Road, Bengaluru, Karnataka, India. *Corresponding author. e-mail: krishnakumar.v@christuniversity.in 137 Explor Anim Med Res. ISSN 2277-470X (Print), ISSN 2319-247X (Online) Vol. 14, Issue 1, 2024 Website: www.animalmedicalresearch.org DOI: 10.52635/eamr/14.1.137-143 Published under the CC BY-NC 4.0 license gynogenesis, polyploidy, and transgenesis [2]. Monosex culture has a significant role in the ornamental fish trade, as these fishes exhibit a marketable sexual dimorphism and in the majority of cases the male fishes are preferred over females due to their overtly pigmented bodies and well-developed fins [3]. A large economic benefit could result from the development of monosex (all-male) populations of ornamental fish due to this marketed preference. Poeciliidae make up over half of the ornamental fish market in India [4, 5]. Poecilia sphenops (common molly) is one of the most popular feeder fishes due to