Tranquilizing and hepatoprotective effects of red-eye tetra (Moenkhausia Forestii) diet fed with Erythrina crista-galli.

This study aimed to assess the leaf aqueous extract composition of Erythrina crista-galli and the effects of its inclusion on the diet of red-eye tetra (Moenkhausia forestii), concerning enzyme content of digestive, hepatic, and oxidation metabolism and pigmentation. Fish (1.78 ± 0.54 g) were divided into groups: fasting (without feeding), control (commercial feed), and treatment (commercial feed with leaf aqueous extract of E. crista-galli) and feeding apparent satiety for 21 days, in the extracted analysis by mass spectrometry, phenolic compost, and flavonoids. The agitation degree and number of dashes, in all supplemented treatments, were lower than those in the control diet when fed for 7 or 15 days. In the digestive enzymatic activity did not differ (p > 0.05). The hepatoprotective treatment group showed lower alanine aminotransferase (ALT) and higher levels of antioxidant catalase (CAT). The results indicated that the aqueous leaf extract of Erythrina crista-galli assists in function maintenance of the liver; and stimulates CAT in red-eye tetra, suggesting that the identified compounds act on the liver and skin, showing hepatoprotective effects and stimulating tranquility.

Moisture content in diets in the co-feeding phase of Pseudoplatystoma sp. influences performance and digestive process.

Live food in the initial life stages of neotropical fish is essential for their development and health; however, it can significantly increase production costs. This study uses complete diets with varying moisture contents (47%, 35%, 24%, and 8%) as a cost-effective alternative in the co-feeding phase of surubim larvae, assessing their influence on development, digestive enzymes, and liver metabolism. In a completely randomized design, 3200 three-day-old Pseudoplatystoma sp. larvae (0.001 g) were distributed evenly among 16 aquariums (20 L), with 200 individuals per aquarium. For the first five days, all larvae were fed Artemia exclusively, after which they were fed experimental diets with varying levels of humidity (47%, 35%, 24%, and 8%) six times a day across four treatments and four replicates. The 21-day feeding trial demonstrated that larvae fed with 24% and 8% moisture diets exhibited increased (p < 0.05) weight gain, final length, and protein efficiency rate. The remaining growth parameters (i.e., specific growth rate and condition factor) did not show significant differences (p > 0.05) among the dietary treatments. Enzymatic analysis revealed that the 47% moisture diet enhanced the amylase and alkaline phosphatase activities, whereas the 24% and 35% moisture diets elevated the lipase and protease activities. The 47% moisture diet also resulted in increased alanine aminotransferase, aspartate aminotransferase, and albumin levels, along with visible hepatic histopathologies in samples, such as visible lipid vacuoles, displacement of the nucleus of the hepatocyte, and increased sinusoid spaces. No significant liver changes were observed in fish fed with other diets. Principal component analysis showed that diets with 8-24% moisture content were the most beneficial during the co-feeding phase of surubim larviculture.