Lactobacillus-Fermented Oecophylla Smaragdina Larvae as a Feed Supplement: Effects on Water Quality, Growth, and Health of Tilapia During the Nursery Phase

The success of the Nile tilapia (Oreochromis niloticus) aquaculture depends on providing nutritionally balanced feed that adequately meets the species' growth requirements, particularly during the nursery phase. Inefficient feed absorption during this period increases production costs, primarily due to higher feed and maintenance expenses. One promising approach to address this challenge involves using alternative feed sources, such as weaver ant (Oecophylla smaragdina) larvae fermented with Lactobacillus bacteria. This study evaluated the optimal dosage of pellet feed fortified with fermented O. smaragdina larvae by analyzing hematological parameters, gut morphology, growth performance, and nitrogen levels in the O. niloticus rearing environment. A completely randomized design was employed, with four dosages tested, each replicated three times. The fermentation dosages of O. smaragdina larvae used were 0 (d₀), 10 (d₁₀), 15 (d₁₅), and 20% (d₂₀), with protein contents of 28, 30.95, 31.02, and 32.25%, respectively. The d₁₅ dosage was the most effective, promoting weight gain, length growth, survival rate, and feed conversion ratio while positively affecting hematological parameters, nutrient absorption, and water quality. Although the d₂₀ dosage resulted in the highest Lactobacillus levels, it produced toxic total ammonia nitrogen and nitrite levels, inducing physiological stress and reduced growth performance. Proper water quality management is essential to mitigate harmful conditions when using dosages higher than 15%.