Short-Term Impacts of Diets Containing an Aloe vera Peel Water Extract on Hypoxia Tolerance and Biochemical Markers in Cyprinus carpio var. Jian

This study aimed to assess how dietary water extract of Aloe vera peel (WEA) affected biochemical markers and hypoxia tolerance in Jian carp (Cyprinus carpio var. Jian). 630 Jian carp (11.77 ± 0.10 g) were fed diets with increasing WEA concentrations (0.0–1.8%) for 15 days. The results showed that short-term feeding of WEA enhanced carp growth performance (p < 0.05). When WEA was added to diets in hypoxic conditions, carp’s duration time (DT) increased and their oxygen consumption rate (OCR) decreased (p < 0.05). In carp blood, feeding WEA improved hematological parameters, such as hematocrit, hemoglobin concentration, mean corpuscular volume, and mean corpuscular hemoglobin content, (p < 0.05) and decreased plasma ammonia levels. Lactic dehydrogenase levels in muscles and gills and transaminases (GOT and GPT) in red blood cells, gills, and hepatopancreas were significantly higher in carp fed diets containing WEA (p < 0.05). Additionally, dietary WEA decreased ROS generation and lipid oxidation in carp respiratory-related tissues and cells by raising both enzymatic antioxidant activities and non-enzymatic antioxidant levels (p < 0.05). Finally, dietary WEA increases hypoxia tolerance in carp by modifying protein and carbohydrate metabolism and boosting the antioxidant capacity of respiratory-related tissues and cells, suggesting that WEA may be a natural method of lowering hypoxic stress in fish.