~ 34 ~ International Journal of Fisheries and Aquatic Studies 2021; 9(2): 34-39 E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 (GIF) Impact Factor: 0.549 IJFAS 2021; 9(2): 34-39 © 2021 IJFAS www.fisheriesjournal.com Received: 16-01-2021 Accepted: 18-02-2021 Barthazar Masengesho Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University, No 2 Nguyen Dinh Chieu Street, Nha Trang City, Vietnam Minh Van Nguyen Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University, No 2 Nguyen Dinh Chieu Street, Nha Trang City, Vietnam Hung Duc Pham Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University, No 2 Nguyen Dinh Chieu Street, Nha Trang City, Vietnam Minh-Hoang Le Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University, No 2 Nguyen Dinh Chieu Street, Nha Trang City, Vietnam Corresponding Author: Minh-Hoang Le Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University, No 2 Nguyen Dinh Chieu Street, Nha Trang City, Vietnam Effects of fish size and feeding rations on growth performance and immune responses of Waigieu sea perch (Psammoperca waigiensis) at juvenile stage Barthazar Masengesho, Minh Van Nguyen, Hung Duc Pham and Minh- Hoang Le DOI: https://doi.org/10.22271/fish.2021.v9.i2a.2438 Abstract Waigieu Sea perch (Psammoperca waigiensis) is one of the most commercially and nutritionally important species. However little research has been done to explore the fish size, feeding rations on growth performance and immune responses of Waigieu Sea perch at juvenile stage. This paper derivers form an in depth study of the effect of feeding rate on growth performance and heamatological parameters. 198 fish of an average initial weight of (17±0.01 g and 8.5±0.01 cm) for group of small size and an average initial weight of (20±0.21g and 11±0.2cm) for group of big size. Juvenile were collected from a luong son hatchery were stocked in 18 tanks (20 L) during 42 days. All fish were fed the same diets contained 44% crude protein at feeding rate of 3, 5 and 7% of body weight with three replicates per treatment fish were fed twice per day at 08:00 and 16: 0 hr. Results revealed that feeding rate tested did not influence survival and there was a significant differences in growth performance and heamotological parameters in both fish size with feeding rates at 5% (P<0.05). There was no significant difference (p>0.05) in whole body composition in all feeding trails. Nevertheless feeding rate of 5% of body weight daily can’t be considered as the optimal feeding rate for Waigieu Sea perch further research should be done on different size and different feeding rate to enhance fish growth and heamatological parameters. Keywords: Waigieu seaperch, Psammoperca waigiensis, fish size, feeding rate, growth rate, immune Introduction Waigieu sea perch (Psammoperca waigiensis) is a marine fish distributed along the coasts of tropical countries in the Asia-Pacific region (Le and Brown 2016, Le et al. 2011, Le et al. 2014a, Le et al. 2014b, Le and Pham 2017, Le and Pham 2018) [10, 11, 12, 13, 14, 15] . Several studies have shown that Waigieu Sea perch are potential candidates for aquaculture and they appear good candidates for a variety of production systems. Early attempts to raise sea perch have been in cages, ponds, and indoor as well as outdoor recirculation systems. However there are few guidelines available that would allow development of formal business plans or cash/flow evaluations. Feed costs are commonly one of the highest annual variable costs in aquaculture (Salgado- Ismodes et al. 2020) [21] . Inadequate feed inputs results in slower growth, slower time to market, and may compromise the immune system, while overfeeding increases cost of production and degrades water quality. Quantifying the near optimal feed rate for new and emerging aquaculture species is an important piece of information. Without this value and associated rates of weight gain, business plans cannot be accurately developed, and development of continuous production scenarios would be challenging (Rupasinghe and Kennedy 2006) [20] . However, optimal feeding rates are not constant throughout the growing cycle of food fish. Optimal feed rates vary at each stage of growth (Marimuthu et al. 2011) [17] . Optimal feed rates are commonly highest at early ages and if those values are known, satiation feeding approaches can be tailored to daily and longer term changes in voluntary consumption, which should gradually decrease over the course of the growing period. The objective of this study was to evaluate the effects of fish size and feeding rates on growth performance and immune responses of Waigieu seaperch juveniles.