Evaluation of Insect Meal Amended Feeds on Fish and Plant Growth Rate in a Coupled Aquaponics System

Abstract

Overfishing for fishmeal (FM) and oil (FO) has decimated populations, limiting their availability, inflating costs of fishmeal for commercial fish feeds worldwide. Incorporating insects as a protein source alongside, or in place of FM or FO, has the potential to increase food security globally in the future. This study evaluated the impact of insect meal (IM) substituted feeds with Tenebrio molitor, mealworm, on the growth rates of both fish and plants. One 12-week trial and one 17-week trial were conducted using T. molitor to produce fish feeds with 0% IM (control), 15% IM, and 25% IM substituted feeds for both. Each trial was performed with 6 separate coupled aquaponics systems (CAS) and both trials reared Nile tilapia (Oreochromis niloticus). The first trial grew butter lettuce (Lactuca sativa), and the second trial grew Ethiopian kale (Brassica carinata), Georgia Southern collard greens (Brassica oleracea), and chickpeas (Sierra kabuli). The CASs for these trials were designed with deep water culture (DWC) beds and floating rafts. The first trial revealed no significant differences in the change of fish biomass between treatments (p ≥ 0.05), and the second trial had a significant difference between the control and 25% IM (p ≤ 0.05). In the first trial the plant biomass increases of the control and the 15% IM treatments were significantly different than the 25% IM treatment (p ≤ 0.05). In the second trial there was no significant difference in collard green biomass between treatments, but there was a significant increase in Ethiopian kale biomass gain from the 25% IM treatment compared to the control (p ≤ 0.05). Lastly, there was a significant difference in chickpea production of viable seeds from tank 1, control, compared to all other CAS (p ≤ 0.05). In conclusion, these results support the potential for IM substituted feeds in aquaponics, and more research needs to be conducted in the future.