Feeding performance of juvenile marble goby (Oxyeleotris marmorata Bleeker, 1852) fed acidified diets

Abstract

The present study aimed to evaluate the feeding performance of juvenile marble goby (Oxyeleotris marmorata) on acidified diets. Five fish meal-based diets at various pH levels (2.5, 3.2, 4.3, 5.3, and 6.0 (control)) were prepared, and each of them was fed to 10 wild-caught O. marmorata juveniles (body length 7.7–9.3 cm; each fish was placed in an aquarium, hence each dietary treatment was in 10 replicates) for 20 days. Throughout the feeding trial, O. marmorata juveniles showed clear increments in the daily ingestion ratio (IR) values of AD 2.5, AD 3.2, and AD 4.3. The control diet and AD 5.3 were almost totally rejected by the fish. On day 20, the IR of AD 2.5 (0.46) and AD 3.2 (0.36) were significantly higher (P < 0.05) than those of AD 5.3 (0.1) and the control diet (0.02). In addition, 70% of fish fed AD 2.5 achieved a high IR value (0.6 – 1.0), and this was the best result among all the treatments (AD 3.2, 60%; AD 4.3 50%; AD 5.3 and control, 10%). These results suggested that acidified diets can be used to wean O. marmorata juveniles, and the recommended pH level was 2.5.

Growth performance and feed utilization of juvenile marble goby (Oxyeleotris marmorata) fed acidified diets

“…Although the acidified diet intake did not support the fish growth, O marmorata showed higher intake of AD 2.5 and AD 3.2 than the other diets (Control,AD 5.3,and AD 4.3) in this study. This result was in agreement with the findings by Teoh et al (2018) and Lim et al (2018) indicating that O. marmorata has strong preference for acidic food. Nevertheless, the present study shows that O. marmorata only accepted the acidified diets for 3 weeks and the intake decreased after the 3 rd week of the feeding trials.…”

“…Nevertheless, the present study shows that O. marmorata only accepted the acidified diets for 3 weeks and the intake decreased after the 3 rd week of the feeding trials. In the behavioural study by Lim et al (2018), the experiment was designed only for 3 weeks, and the good feeding performance of O. marmorata on AD 2.5 and AD 3.2 was reported only up to that period. Therefore, in light of the results of the present study, feeding O. marmorata with the acidified diets for an extended period (> 3 weeks) is not recommended.…”

“…Teoh et al (2018) further confirmed the preference of O. marmorata for diet of pH = 2.4 -3.0 through behavioural assays by replacing the organic acids with solely hydrochloric acid. Indeed, the length of weaning period can be shortened and the number of successfully weaned fish increased when the O. marmorata juveniles were weaned using the pH 2.5 and pH 3.2 acidified diets, rather than the control diet (pH 6.0) (Lim et al, 2018). It is known that feeding the acidified diets to fish can enhance their growth performance and feed utilization (Lückstädt, 2008;Phromkunthong et al, 2010;Tabrizi et al, 2012;Sherif and Doaa, 2013;Zhu et al, 2014;Shah et al, 2015).…”

Using integrative physiology to optimise diets for sustainable aquaculture

“…The concept of manipulating stomach acidity through the addition of acid to feeds or through the use of ingredients with reduced buffering capacity has been used in the production of animal feeds since the 1980's (Jasaitis et al, 1987;Lückstädt, 2007Lückstädt, , 2008Prohászka & Baron, 1980). In fish, diet acidification has been used to improve feed preservation (Lückstädt, 2008), fish growth (Ng & Koh, 2017;Soltan et al, 2017), phosphorous digestibility (Sugiura et al, 2006) and enhance feed intake (Lim et al, 2018).…”

“…However, looking at this question from an alternative angle, it is likely that lowering the pH of a fish feed through the addition of acids may reduce the physiological costs associated with digestion. To date we know that the use of acidifiers in fish diets can improve feed preservation (Lückstädt, 2007), enhance feed intake (Lim et al, 2018), fish growth and phosphorous digestibility (Sugiura et al 2006), but it remains unknown if increasing the acidity of a pelleted diet can influence the physiological costs during digestion in fish. Acidifying a pelleted fish diet could decrease the physiological costs associated with gastric acid secretion and recovery from the blood alkaline tide to inform feed production in aquaculture.…”