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Ammonia is a critical hazardous nitrogen metabolic product in aquaculture. Despite trials for its control, ammonia intoxication remains one of the most critical issues to overcome. In this study, we explored the modulatory effect and potential mechanism by which Yucca schidigera extract (YSE) can ameliorate ammonia intoxication-induced adverse effects on tilapia health and metabolism. A total number of 120 Nile tilapia were evenly assigned into four groups with three replicates each. The first group served as normal control group, the second group was exposed to ammonia alone from the beginning of the experiment and for four weeks. The third group was supplied with YSE in water at a dose of 8 mg/L and exposed to ammonia. The fourth group was supplied with YSE only in water at a dose of 8 mg/L. YSE supplementation succeeded in improving water quality by reducing pH and ammonia levels. Moreover, YSE supplementation markedly alleviated chronic ammonia-induced adverse impacts on fish growth by increasing the final body weight (FBW), specific growth rate (SGR), feed intake and protein efficiency ratio (PER) while reducing the feed conversion ratio (FCR) via improvements in food intake, elevation of hepatic insulin-like growth factor (ILGF-1) and suppression of myostatin (MSTN) expression levels with the restoration of lipid reserves and the activation of lipogenic potential in adipose tissue as demonstrated by changes in the circulating metabolite levels. In addition, the levels of hepato-renal injury biomarkers were restored, hepatic lipid peroxidation was inhibited and the levels of hepatic antioxidant biomarkers were enhanced. Therefore, the current study suggests that YSE supplementation exerted an ameliorative role against chronic ammonia-induced oxidative stress and toxic effects due to its free radical-scavenging potential, potent antioxidant activities and anti-inflammatory effects.

The present study evaluated the enhancement of the growth rate, intestinal health, immune-related genes, and resistance against suboptimal water temperature in common carp (2.01 ± 0.02 g) by dietary paraprobiotics. Fish were fed dietary heat killed Lactobacillus plantarum (LP20) at 0 (control), 50, and 100 mg/kg for 2 months. After the feeding trial fish were exposed to suboptimal water temperature averaged 13.22 ± 0.44 °C for 48 h. The final body weight, weight gain, specific growth rate, and feed conversion ratio of fish fed LP20 at 100 mg/kg were significantly enhanced (P < 0.05). The villi length and width were increased in fish fed LP20 at 50 and 100 mg/kg when compared to the control (P < 0.05). The crypt depth was increased by increasing LP20 in a dose dependent manner with the highest value in the group of fish fed 100 mg/kg (P < 0.05). The number of goblet cells showed higher number in fish fed LP20 at 50 and 100 mg/kg than the control group (P < 0.05). The expression of catalase (CAT) gene did not show any changes in transcription before the thermal stress however after thermal stress fish fed 50 mg/kg had upregulated CAT followed by those fed 100 mg/kg. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) gene expressions showed upregulations in fish fed 50 mg/kg before the thermal stress but after the thermal stress fish fed 100 mg/kg had the highest level of mRNA transcriptions for GPx and SOD genes. In the same manner, the expression of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and interleukin 10 (IL-10) were significantly upregulated in fish fed LP20 at 50 mg/kg before the thermal stress whereas the expression of these genes was upregulated in fish fed 100 mg/kg. In conclusion, using LP20 at 50−100 mg/kg resulted in enhancing the growth rate, intestinal morphometry, immune and antioxidative related genes. Accordingly, common carp showed high resistance against suboptimal water temperature stress.

This study aimed to evaluate the effects of different monochromatic LED light colors (blue “BL”, red “RL”, green “GL” and white “WL”) in addition to natural day light (NL) on the growth performance, behavior and immune-physiological responses of goldfish (Carassius auratus). Fish (N = 75, 4.483 ± 0.061 g) were arbitrarily allocated to five groups (BL, RL, GL, WL and NL) in triplicates and fed a commercial diet (400 g/kg crude protein, 80 g/kg crude lipid) for 2 months. There was a significant improvement in final body weight, weight gain, weight gain rate, feed conversion ratio, specific growth rate, length, hepato-somatic and viscerosomatic index of fish reared under BL in respect to the other tested groups (p ≤ 0.05). Fish reared in BL showed better behavior response in form of lower ventilation frequency, longer reaction time and swimming duration in the novel object test, as well as shorter latency to first movement in duration of appetite inhibition test compared to the other experimental groups (p ≤ 0.05). Immune-physiological responses were improved in fish reared under BL followed by GL in respect to the other groups (p ≤ 0.05). This was manifested by higher red blood cells, hemoglobin, total protein, albumin (A), globulin (G), A/G ratio, lysozyme activity, as well as lower neutrophils / lymphocytes ratio, glucose, and cortisol. Despite of absence of statistical significance effect of light color on the relative expression of transforming growth factor beta 1, tumor necrosis factor alpha and interleukin-1 beta 2 genes, slight up-regulation of immune-related genes was observed in the fish reared in BL. In conclusion, rearing of goldfish under monochromatic BL improves their performance, behavior, and immune-physiological responses to stress without any adverse effects on water quality.

The present study evaluated the possible synergistic impacts of sodium butyrate and Spirulina platensis as a feed additive on growth performance, carcass composition, blood health, and intestinal histomorphology of Nile tilapia (Oreochromis niloticus). A control and three treated diets were supplemented with sodium butyrate (SB) 350 mg, Spirulina platensis (SP) 1g and a mixture of 350 mg SB and 1g SP/kg diet (SB/SP) respectively, were fed for monosex Nile tilapia (12.5± 0.50 g, n=120) for two months. The results revealed higher growth performance (final weight, weight gain, weight gain rate, SGR and PER) compared to control group (CG) (P

β-glucans are widely-known immunostimulants that are profusely used in aquaculture industry. The present study was conducted to evaluate the effect of different in-feed doses of β-1,3/1,6-glucans on the expression of antioxidant and stress-related genes (GST, HSP-70, Vtg), inflammation related genes (Il-8, TNFα, CXC-chemokine and CAS) and adaptive immune-related genes (MHC-IIβ, TLR-7, IgM-H, and Mx) of Oreochromis niloticus challenged and non-challenged with Streptococcus iniae. Six experimental groups were established: non-challenged control (non-supplemented diet), challenged control (non-supplemented diet), non-challenged supplemented with 0.1% β-glucan, challenged supplemented with 0.1% β-glucan, non-challenged supplemented with 0.2% β-glucan and challenged supplemented with 0.2% β-glucan. Fish were fed with β-glucan for 21 days prior challenge and then sampled after 1, 3 and 7 days post-challenge. In non-challenged group, variable effects of the two doses of β-Glucans on the expression of the studied genes were observed; 0.1% induced higher expression of HSP70, CXC chemokine, MHC-IIβ and MX genes. Meanwhile, 0.2% induced better effect on the expression of Vtg, TNF-α, CAS and IgM-H, and almost equal effects of both doses on GST and IL8. However, with the challenged group, 0.2% β-Glucans showed better effect than 0.1% at day one post challenge through significant up-regulation of GST, HSP, IL8, TNF-α, CXC, and MHC-IIβ, meanwhile, the effect of 0.1% was only on the expression of HSP70, MHC-IIβ, and TLR7 at day 3 post challenge. No stimulatory role for both doses of β-Glucans on the expression of almost all genes at day 7 post-challenge. We conclude that both doses of β-glucan can modulate the antioxidant, inflammation, stress and immune-related genes in Nile tilapia, moreover, 0.2% β-Glucans showed better protective effect with Streptococcus iniae challange.