Growth, water quality and oxidative stress of Nile tilapiaOreochromis niloticus(L.) in biofloc technology system at different pH

Abstract

The objective of this study was to demonstrate the pH effects on growth, survival, water quality, proximal composition of bioflocs and oxidative stress of Nile tilapia in biofloc technology (BFT) system. Twenty‐five fish (3.68 ± 0.93 g) were distributed in each tank (useful vol. 37.5 L), utilizing treatments with pH 8.3, 7.5 and 6.5 at 60 days. During the experiment, the oxidation of total ammonia was similar among the treatments. However, the NO2−‐N oxidation was slower at pH 6.5 (10.1 ± 1.0 mg/L) compared to pH 7.5 (7.0 ± 0.6 mg/L) and 8.3 (7.1 ± 1.5 mg/L). The final weight was higher for pH 7.5 treatment (44.1 ± 0.9 g) compared to pH 8.3 (37.1 ± 3.9 g), while the pH 6.5 (40.4 ± 4.1 g) was like to the other treatments. Moreover, the survival, daily growth rate and the food conversion rate were not affected by treatments. When evaluating physiological and biochemical parameters, no alterations were detected, therefore, indicating that fish have a good health status. Thus, the present study demonstrates that BFT for a Nile tilapia nursery, utilizing pH 6.5–7.5, promotes the best results in terms of growth, net yield and efficiency.

Nile tilapia nursery feeding management in a biofloc system

“…It was observed that the higher the feed rate, the lower the relative consumption of alkalizer, which ranged from 13.45% to 15.62% of the Ciência e Agrotecnologia, 2022 amount of feed offered. These values are similar to those reported by Martins et al (2017Martins et al ( , 2019, who used sodium bicarbonate as a carbon source in Nile tilapia nursery. The treatment with the highest feeding rate (TE) presented the highest consumption of alkalinizer per produced fish biomass, differing from the other treatments (Table 2).…”

“…Silva et al ( 2020) also observed higher values of SS and TSS with higher feeding rates, having reportedmaximum values of 225 mL L -1 and 1,450 mg L -1 of solids throughout the rearing of tilapia juveniles when fed with 100% of the satiety. Tilapia nursery studies in a biofloc system demonstrated a wide variation in the values of SS (0.5 to 65 mL L -1 ) and TSS (200 to 1,600 mg L -1 ) (Martins et al, 2017, Lima et al, 2018, Martins et al, 2019, Correa et al, 2020, Durigon et al, 2020, Hisano et al, 2020, Vicente et al, 2020. In this study, the solids were managed to maintain mean values close to 30 mL L -1 and 600 mg L -1 .…”

Effects of three carbohydrate sources on water quality, water consumption, bacterial count, growth and muscle quality of Nile tilapia ( Oreochromis niloticus ) in a biofloc system

“…However, it is unlikely that this low pH had adverse effect on tilapia growth or on the nitrification process (Day, Salie, & Stander, 2016). Martins, da Rosa, Tarouco, and Robaldo (2019) found that pH of 6.5–7.5 promoted best growth of Nile tilapia fingerlings in BFT. In this study, the recorded alkalinity in the BFT treatments is lower than the range of 100–150 mg/L recommended by Hargreaves (2013) for better biofloc formation and establishment of the nitrifying bacteria.…”

The Effect of Adding Molasses in Different Times on Performance of Nile Tilapia (Oreochromis niloticus) Raised in a Low-Salinity Biofloc System

“…The lipid content of bioflocs is usually at the low level, but the presence of essential fatty acids has significantly increased their nutritional value (Ju et al, 2008;Khatoon et al, 2016). The type of carbon source (Khanjani et al, 2017), C: N ratio (Minabi et al, 2020), water salinity (Ekasari et al, 2010;Khanjani et al, 2020b), feeding level (Khanjani et al, 2016), the source of light and its intensity (Coyle et al, 2011), pH (Martins et al, 2019) and the type of microbial community (Ahmad et al, 2017) are considered as parameters affecting the biochemical composition of bioflocs.…”