Effects of humic acid on nutrient removal efficiency of aquatic duckweed (Lemna minor) and both growth performance, and hemato-biochemical parameters of Nile tilapia (Oreochromis niloticus) cultured in water recirculating system.

This study was carried out to evaluate the effects of humic acid (HA) on the nutrient removal efficiencies of aquatic duckweed plant (Lemna minor) from a water recirculating system used to culture Nile tilapia (Oreochromis niloticus) fish for 30 days. The HA was added to water at three concentrations of 0 (Control), 1.5, and 3 mg/L in triplicate. Water quality parameters, growth performance, and some hemato-biochemical parameters of the fish in variable HA concentrations were compared. The total ammonia nitrogen (TAN) and total phosphorous (TP) removal efficiency of L. minor increased with increasing the HA concentration from 0 mg/L to 3 mg/L (p < 0.05). The concentration of nitrate (NO3-) in the HA-3 mg/L was higher than that in the other groups on days 20 and 30 of the fish cultivation period (p < 0.05). The growth performance of fish improved in the HA-3 mg/L compared to the other groups. The addition of different concentrations of HA to water had no adverse effect on the hematological properties of the Nile tilapia. The plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) levels in the HA-0 mg/L and HA-1.5 mg/L groups were higher than in the HA-3 mg/L (p < 0.05). No significant differences in the plasma glucose and cholesterol levels were observed between the HA-groups (p > 0.05), while the triglyceride level increased in the HA-3 mg/L compared to the control (p < 0.05). These results indicated that adding HA to water could be an effective method to enhance the bioremediation performance of the aquatic duckweed plants as biofilter and thus improve water quality, subsequently, fish growth performance in RASs.

The current study applied aquatic duckweed plant (Lemna minor) as a new biofilter in a water recirculating system used to culture Nile tilapia (Oreochromis niloticus) fish. The effects of three concentrations of humic acid (HA) as water additive on the nutrient removal efficiency of L. minor from water were investigated. HA improved bioremediation performance of the aquatic duckweed plant.

Non-specific immunity promotion in response to garlic extract supplemented diets in female Guppy (Poecilia reticulata).

In the present study, the effect of aqueous garlic (Allium sativum) extract on skin mucus immune parameters of Poecilia reticulata was evaluated. A total of 240 P. reticulate juveniles, weighing 0.013 ± 0.001 g, were randomly stocked in 12 experimental glass tanks at a density of 30 fish per tank. The fish were fed with diets supplemented with garlic extract at the concentrations of 0, 0.10, 0.15, and 0.20 ml kg-1 of diet three times a day at a ratio of 2.5% of their body weight for 80 days. Results of the study showed that, lysozyme activity increased significantly in the skin mucus of garlic-treated Guppy (P < 0.05). Values of ACH50 significantly increased (P < 0.05) in fish by increasing concentration of garlic extract from 0 to 0.15 ml kg-1 in diet. ACH50 also showed a significant declining trend (P < 0.05) by increasing concentration of garlic extract from 0.15 to 0.20 ml kg-1. Total Ig content was enhanced significantly in 0.15 and 0.20 ml kg-1 treatments as well. ALP activity significantly increased in garlic-fed treatments compared to the control. Inclusion of garlic extract in diet was found to have no significant effect on final body weight and weight gain. Results revealed that, administration of 0.15 mL of garlic extract per kg feed is suggested to obtain optimal skin mucus immunity in P. reticulata.

Improvement of non-specific immunity, growth, and activity of digestive enzymes in Carassius auratus as a result of apple cider vinegar administration to diet.

This study was conducted to evaluate the effects of apple cider vinegar (ACV) administration on non-specific immunity of serum and skin mucus, growth indices, and activity of digestive enzymes (amylase, lipase, and protease) in Carassius auratus. For this purpose, 180 fish (weighing 7.35 ± 0.19 g) were allocated to 4 treatment groups with 3 replications in a completely randomized design. Fish were fed for 105 days using a basal diet supplemented with 0% (control), 1% (T 1), 2% (T 2), and 4% (T 3) ACV (contained 5% acetic acid). Results showed a significant increase in lysozyme activity, ACH50, and total immunoglobulin of skin mucus in fish fed with T2 diet (p < 0.05). Total immunoglobulin and lysozyme activity were significantly lower in the serum of fish fed with control diet than those fed with the mentioned treatment (p < 0.05). The highest value was observed in fish fed with T2 diet. Minimum (p < 0.05) complement activity (1.52 ± 0. 25 U ml-1) was observed in fish fed with control diet. The mean of the final weights (17.35 ± 1.39 g), daily growth (1.0 ± 0.01 g), and specific growth rate (2.19 ± 0.14) was significantly higher in T3 diet group than the controls (p < 0.05). While the highest amylase-specific activity was observed in the controls (p < 0.05), there was a significant increase in specific activity of protease, lipase, and alkaline phosphatase in T2 diet group (p < 0.05). According to the results of this study, the inclusion of a limited quantity of ACV (4%) into the diet can improve immunity and growth parameters in C. auratus.