International Journal of Agriculture, Environment and Bioresearch Vol. 4, No. 03; 2019 ISSN: 2456-8643 www.ijaeb.org Page 102 EFFECTS OF SOYBEAN MEAL ON NEW MUSCLE GENERATION AND GROWTH OF SILVER BARB, BARBONYMUS GONIONOTUS Halima Jahan, Mst. Arzu Parvin, Rabeya Akter and Zakir Hossain* Department of Fisheries Biology and Genetics Bangladesh Agricultural University, Mymensingh-2202, Bangladesh ABSTRACT The aim of this study was to evaluate the effects of substituting fishmeal (FM) with soybean meal (SM) on new muscle generation of silver barb, Barbonymus gonionotus. Five diets were prepared with SM 0 (FM 100), SM 25 (FM 75), SM 50 (FM50), SM 75 (FM25) and SM 100% (FM 0%) by replacing FM with SM. Each diet was fed to B. gonionotus having initial weight of 8.80 ± 3.11 g to apparent satiation twice a day for six months. During the 120th days, the growth were significantly (P< 0.05) higher in fish fed with SM50 diets compared to SM0 diets. But in 150th days, growth were significantly (P<0.01) higher in fish fed with SM25 diets compared to SM0 diets. Finally during 180th days, growth were significantly (P<0.1) higher in fish fed with SM50 and SM25 diets compared to SM100 diets. There was a significantly (P< 0.05) increased number of muscle fiber atSM50, SM25 and SM0 diets compared to SM100. Diameter of muscle fiber (μm) was significantly (P<0.01) increased at SM50, SM25 and SM0 diets compared to SM100 diet. The results of the present study indicated that substitution of upto50% SM with FM enhanced the muscle growth by promoting hyperplasia and hypertrophy in B. gonionotus. Keywords: Muscle fiber, Diets, Protein source, Hyperplasia, Hypertrophy 1. INTRODUCTION Bangladesh is considered one of the most suitable countries in the world for freshwater aquaculture. Success in aquaculture depends primarily on the use of quality fish feed. Reducing the level of fishmeal (FM) in fish diets is a major challenge for intensive aquaculture. Potential substitutes should match both the high protein needs of fish and their indispensable amino acid requirements. Several trials have been conducted with different aquaculture species in order to find plant ingredients or combinations of different plant ingredients that might replace FM. It is now well established that FM can be partially substituted by alternative protein sources but the success of total substitution of FM without growth impairment has been very limited (Kaushik et al., 1995; Rodehutscord et al., 1995; Watanabe et al., 1998). Muscle growth mechanisms in teleosts such as salmonids that reach a large adult body size differ from those occurring in other animals such as mammals and birds. Indeed, muscle enlargement in fish occurs both by hypertrophy (i.e., increase in size of existing muscle fibres) and by hyperplasia (i.e., recruitment of new muscle fibres) not only before hatching but also during a large part of post-hatching life (Rowlerson and Veggetti, 2001). In most teleosts axial skeletal muscle mass represents more than 60% of body mass. These muscles consist mainly of deep fast