One of the most important aquaculture species in the North Central Region and the Great Lakes is yellow perch (Perca flavescens); the production is restricted by the high feed costs as the fish relies on fishmeal (FM). Some studies have evaluated fish meal (FM) replacement in yellow perch diets using plant protein, with soybean meal (SBM) being one of the most promising plant protein replacements. However, high inclusion levels of SBM may cause intestinal inflammation and damage, which reduces growth and feed efficiency due to the presence of antinutritional factors (Kasper et al. 2007; Schaeffer et al. 2011; Kemski et al. 2018, Kumar et al. 2019). Hence, Kasper et al. (2007) recommended SBM inclusion levels up to 30%, since a significant reduction in feed consumption was evident at 40% SBM inclusion.
The use of Aloe vera (Aloe barbadensis, AV), which is a phytogenic additive with anti-inflammatory and immunostimulatory effects that have been shown in a number of fish species, is one possible solution. A feeding trial was carried out to assess this approach with diets containing different levels of SBM included (0%–65%) with and without Aloe vera supplementation. A flow through system composed of 27 circular tanks, 26.5 Liters each (nine treatments with three replicates per treatment) was used for the feeding study. Twenty yellow perch fingerlings were stocked in each tank. Water temperature, and dissolved oxygen were measured on a daily basis. Measured production parameters included growth performance, total yield, feed conversion ratio, protein efficiency, intestinal morphology and survival.