Effect of Salinity on Survival, Growth, Body Composition, Oxygen Consumption, and Ammonia Excretion of Juvenile Spotted Scat

Abstract

The effects of five salinities (5, 10, 20, 30, and 35‰) on the survival, growth, body composition, oxygen consumption, and ammonia excretion of juvenile Spotted Scat Scatophagus argus (initial body size 3.3–3.4 cm body length and 2.0–2.3 g; final body size: 5.5–5.6 cm body length and 9.2–9.8 g) were studied. Salinity did not affect survival (>94%) or oxygen consumption rate (OCR) significantly, but it did affect growth, ammonia excretion rate (AER), and body composition. The growth rate was related to the combined effect of food intake (3.1–3.2%/d) and feed conversion efficiency (56.8–60.2%). The highest slope of the body length/weight with rearing time regression equation at 5‰ salinity was 0.0333/0.1137, which indicated that the growth rate of the fish at 5‰ salinity was higher than that of those at the other salinities for 70 d at 24.4 ± 0.4°C. The ammonia excretion rate decreased significantly with the increase of salinity. Low O:N ratios (5.6–19.2) occurred at salinities ranging from 5‰ to 35‰, indicating a protein‐dominated catabolism. Salinity affected crude protein content significantly, and high salinity was beneficial to protein deposition. The results indicated that juvenile Spotted Scat could adapt to a wide range of salinity, from 5‰ to 35‰. However, it is recommended that juveniles be cultured at low salinity (5‰).

Effects of salinity on growth performance of early juveniles of Spotted scat (Scatophagus argus)

“…However, salinity did not affect respiratory metabolism but did affect ammonia excretion rate in spotted scat juvenile (Xu et al, 2020). Moreover, low salinity could promote better digestion and absorption, which leads to better growth (Xu et al, 2020). In this study, no significant difference in fish growth could be explained by the short time of salinity exposure.…”

“…Accordingly, at isotonic point, the energetic cost for osmoregulation is lower and the energy saved is sufficient enough to increase the growth of fish (Mookkan et al, 2014). However, salinity did not affect respiratory metabolism but did affect ammonia excretion rate in spotted scat juvenile (Xu et al, 2020). Moreover, low salinity could promote better digestion and absorption, which leads to better growth (Xu et al, 2020).…”

“…Spotted scat has been well known as a euryhaline fish with strong adaptability to salinity in nature (Gupta 2016), however, the appropriate salinity preferences for growth and survival have not yet been evaluated, especially in terms of early growth stages. Importantly, salinity affects the standard metabolic rate of fish (Ern and Esbaugh, 2018), fish ingestion rate, conversion efficiency, metabolism, and hormone secretion, thus affecting the growth of the body and the accumulation of nutrients (Boeuf and Payan, 2001;Ern et al, 2014;Xu et al, 2020). Therefore, this study proposed to evaluate effects of salinity on survival and growth performance of S. argus at early juvenile stage for optimization the production technology leading to the sustainable production of S. argus for mariculture.…”

Growth Performance, Physiological Responses, and Histoarchitectural Changes in Juvenile Pangasianodon hypophthalmus under Different Environmental Salinities

“…Regarding the moisture content (%), we found an inverse relationship between the moisture content (%) in the body of the exposed fish and salinity levels. This relationship may be attributed to the fact that these fish may absorb more water to be acclimatized to the new salinity environment and maintain normal physiological homeostasis [49]. Generally, the changes in fish body CP and CL are associated with their synthesis in the fish body and/or consumption as energy sources.…”