Reproductive responses of female saline-adapted Nile tilapia Oreochromis sp. to dietary Spirulina sp. supplementation

Abstract

Saline-adapted Nile tilapia (Oreochromis sp.) is a freshwater tilapia fish that was selectively adapted to brackish water aquaculture. However, its sustainable production is often constrained by the suboptimal reproductive performance of female broodstock, creating a bottleneck in seed supply. This study aimed to evaluate the effects of dietary Spirulina sp., a microalga rich in protein and bioactive compounds, on key reproductive indices. The experiment was arranged in a completely randomized design (CRD), in which female broodstock were randomly allocated to four dietary treatments containing graded levels of Spirulina supplementation: 0% (control), 1%, 2%, and 3%, with three independent replicates per treatment. The primary productive parameters assessed were fecundity, egg diameter, egg hatching rate, and survival rate. The results demonstrated a significant, dose-dependent improvement in all reproductive parameters (P<0.05). The 3% Spirulina sp. diet yielded the most substantial outcomes, leading to an increase in fecundity and achieving near-optimal hatching (98.75%) and 7-day larval survival rates (96.27%) compared to the control. Water quality remained stable and consistent across all treatments, confirming that the observed effects were directly attributable to dietary intervention. In conclusion, dietary supplementation with 3% Spirulina sp. is a highly effective strategy for enhancing the reproductive performance of female saline-adapted Nile tilapia. This microalga serves as a potent functional feed additive, offering a sustainable approach to improve seed quality and quantity in brackish-water aquaculture systems.

Keywords: brackish water aquaculture, fecundity, Nile tilapia, reproductive performance, spirulina