This study compared the growth and biomass production of Isochrysis galbana under hetero-, mixo-, and phototrophic conditions using different organic carbon sources. The growth of I. galbana was inhibited in heterotrophy but was enhanced in mixotrophy compared to that in phototrophy. Subsequently, the influences of organic carbon and environmental factors (light and salinity) on the growth of I. galbana were further investigated. Algal dry weight increased as glycerol concentrations increased from 0 to 200mmol and the highest algal production occurred at 50mmol glycerol. At a range of light intensities of 25200μmol photons m2 s2, the highest algal growth rate occurred at 100 photons μmol m2 s2. The growth of I. galbana was significantly affected by photoperiod, and the maximal dry weight was obtained at 12h light and 12h dark. In the salinity test, I. galbana could grow in a wide range of salinities from 10 to 65, but the 35salinity was optimal. This study suggests that the growth and production of I. galbana can be improved using mixotrophic culture at 50mmol glycerol in 35salinity.

A technique called biofloc technology (BFT) is an environmentally friendly method for aquaculture in which a successful growing cycle depends on the maintenance and monitoring of water quality parameters. Studies have revealed that improving water quality in BFT and maintaining the safety range of the parameters can help to increase the growth performance of cultured species. Following a systematic review of the literature, a meta-analysis was performed to explore how some important water parameters such as pH, dissolved oxygen (DO), nitrite (NO₂N), nitrate (NO₃N), ammonia (NH₃N), total ammonia nitrogen (TAN), total suspended solids (TSS), and alkalinity were influenced by different BFT systems. The PRISMA screening process was followed, and 33 studies were eligible for the meta-analysis. The meta-analyses showed that NO₂N and TSS were significantly affected by BFT, while pH, DO, NO₃N, NH₃N, TAN, and alkalinity were not significantly influenced by this system. The analyses revealed that NO₂N had a significant negative effect size due to BFT, whereas TSS showed a significant positive effect size. The study also revealed some publication bias in which few experiments of some studies showed extremely positive and negative effect sizes due to BFT application in the system. Overall, the findings suggest clear evidence of the profound influence of BFT on the water quality parameters in different aquaculture systems, suggesting the future development of BFT for sustainable and environmentally friendly aquaculture production.

In euryhaline teleost black porgy, Acanthopagrus schlegelii, the glucocorticoid receptor (gr), growth hormone receptor (ghr), prolactin (prl)-receptor (prlr), and sodium–potassium ATPase alpha subunit (α-nka) play essential physiological roles in the osmoregulatory organs, including the gill, kidney, and intestine, during osmotic stress. The present study aimed to investigate the impact of pituitary hormones and hormone receptors in the osmoregulatory organs during the transfer from freshwater (FW) to 4 ppt and seawater (SW) and vice versa in black porgy. Quantitative real-time PCR (Q-PCR) was carried out to analyze the transcript levels during salinity and osmoregulatory stress. Increased salinity resulted in decreased transcripts of prl in the pituitary, α-nka and prlr in the gill, and α-nka and prlr in the kidney. Increased salinity caused the increased transcripts of gr in the gill and α-nka in the intestine. Decreased salinity resulted in increased pituitary prl, and increases in α-nka and prlr in the gill, and α-nka, prlr, and ghr in the kidney. Taken together, the present results highlight the involvement of prl, prlr, gh, and ghr in the osmoregulation and osmotic stress in the osmoregulatory organs (gill, intestine, and kidney). Pituitary prl, and gill and intestine prlr are consistently downregulated during the increased salinity stress and vice versa. It is suggested that prl plays a more significant role in osmoregulation than gh in the euryhaline black porgy. Furthermore, the present results highlighted that the gill gr transcript’s role was solely to balance the homeostasis in the black porgy during salinity stress.

Despite the widespread practice of using probiotics in aquaculture for their potential benefits, the consistency of their impact on disease resistance in fish is still being scrutinized. This study aimed to address this gap by investigating the influence of the probiotic Pediococcus acidilactici (PCA) on hematological indices, body composition, serum metabolites, water quality, growth metrics, the transcriptomic profile of genes related to immune function, and the ability of red tilapia (Oreochromis niloticus × O. mossambicus) to resist challenge with the bacterial pathogen Aeromonas hydrophila. A total of 180 tilapia fingerlings (average weight 17.10 ± 0.46 g) were distributed into four groups and fed a basal diet supplemented with 0 (PCA0), 1 (PCA1), 2 (PCA2), and 3 (PCA3) g of PCA per kg of diet for 63 days. Water quality analysis indicated a significant decrease in both salinity and dissolved oxygen concentrations in all PCA-supplemented groups compared to a PCA-free diet (P < 0.05). Fish fed diets having 2 or 3 PCA had superior FBW, SGR, and ADG, while these levels significantly improved the FCR compared to the untreated diet (P < 0.001). In fish supplemented with PCA, body composition analysis showed a statistically significant increase in protein and ash content, accompanied by a statistically significant decrease in lipid content (P < 0.05). Furthermore, dietary PCA significantly enhanced phagocytic index, and serum IgG and IgM levels in a dose-dependent response. Notable improvements in hematological variables and blood protein fractions were observed in the PCA2 and PCA3 groups compared to other groups (P < 0.05). Dietary PCA administration sustained liver enzymes and kidney functions (P < 0.05). Dietary supplementation with PCA resulted in a significant upregulation (P < 0.05) of growth-related genes (GH, IGF-1, and IGF1-R) and immunity-associated genes (CXC chemokine, IL8, and IL1β) in a dose-dependent manner. Furthermore, dietary PCA improved the histological structure of the liver and enhanced intestinal integrity in Tilapia. Following pathogen challenge, the survival rate was significantly higher in all PCA-supplemented groups compared to the control group, with the highest survival observed in the PCA3 group. In summary, this research highlights the significant benefits of dietary Pediococcus acidilactici supplementation at 2 and 3 g/kg for improving growth, blood physiology, immunity, and disease resistance in red tilapia. These findings underscore the potential of Pediococcus acidilactici as a practical and effective strategy for enhancing productivity and sustainability in red tilapia aquaculture.