Environmental structural enrichment is a method to increase environmental heterogeneity, which may reduce stress and improve animal welfare. Previous studies have shown that environmental enrichment can increase the growth rate, decrease aggressive and anxiety-like behaviors and reduce cortisol levels in animals. The purpose of this study was to investigate the effects of environmental enrichment on the behavior (boldness and aggressiveness) and growth (total length, standard length, weight) of the Nile tilapia (Oreochromis niloticus). Boldness, aggressiveness, total length, standard length, and weight were weekly measured over a 13-week period (during weeks 0, 1, 3, 5, 7, 9, and 11) for fish housed in three treatment tanks: no structural enrichment (NSE), moderate structural enrichment (MSE), and heavy structural enrichment (HSE). Significant differences were detected in boldness, aggressiveness, total length, standard length and weight among the three treatments as the weeks progressed (P< 0.05). Boldness was the highest in fish reared in tanks with heavy structural enrichment as the weeks progressed (P< 0.05). However, aggressiveness was lowest across weeks in fish reared in tanks with heavy structural enrichment (P< 0.05). The highest levels of growth, in terms of weight (P< 0.05), total length (P< 0.05), and standard length (P< 0.05), were recorded in the fish reared in tanks with heavy structural enrichments across weeks (P< 0.05). This study suggests that the growth of Oreochromis niloticus might be influenced by the structural enrichment of their rearing environment. Therefore, future related studies should consider environmental structural enrichment to enhance the growth of Oreochromis niloticus.