Use of Vertically–Suspended Environmental Enrichment during Intensive Rearing of Juvenile Bluegill.

Vertically-suspended environmental enrichment is used to improve the structural complexity of fish rearing units. This study evaluated the effects of vertically-suspended metal rods as environmental enrichment in Recirculating Aquaculture System (RAS) circular tanks containing bluegill (Lepomis macrochirus). At the end of the 55-day experiment, ending tank weight, gain, and percent gain were significantly greater in unenriched tanks compared to those with vertically-suspended environmental enrichment. Feed conversion ratio was significantly lower in unenriched tanks as well. However, individual fish length, weight, condition factor, and specific growth rate were not significantly different between bluegill reared in tanks with vertically-suspended environmental enrichment and those reared in control unenriched tanks. These results indicate that vertically-suspended environmental enrichment does not improve bluegill growth, at least with the size of fish and enrichment used in this study.