Insect-based fish feed in decoupled aquaponic systems: Effect on lettuce production and resource use

Area of Science:

• Aquaculture and Aquaponics
• Sustainable Agriculture
• Insect Bioconversion

Background:

• Insect meal offers a sustainable alternative to conventional fish meal in aquaculture feeds.
• Research on insect meal-based diets in aquaponics, particularly regarding wastewater effects on plant growth, is limited.
• Black Soldier Fly (BSF) meal is a key insect protein source for sustainable aquaculture.

Purpose of the Study:

• To compare the effects of fish wastewater from diets based on fish meal (FM) and BSF meal on lettuce growth and resource use in aquaponics.
• To evaluate BSF meal as a sustainable alternative to FM in tilapia feeds for aquaponic systems.
• To assess the impact of these diets on nutrient solution composition and inorganic fertilizer requirements.

Main Methods:

• Decoupled aquaponic systems were used with tilapia fed either FM or BSF diets.
• Lettuce growth parameters (weight, leaf count, chlorophyll) were measured.
• Nutrient solutions were analyzed for micro- and macronutrients, and water and fertilizer consumption were quantified.

Main Results:

• Lettuce yield (fresh/dry weight, leaf number, chlorophyll) was comparable across all treatments (BSF meal, FM, and hydroponics control).
• Water consumption per plant was similar among treatments.
• Inorganic fertilizer use was reduced by 32% in FM and BSF treatments compared to the hydroponics control.
• BSF diets resulted in lower sodium concentrations in the nutrient solution compared to FM diets.

Conclusions:

• BSF meal-based diets are a promising and sustainable alternative to FM-based diets in aquaponics, showing no negative impact on lettuce growth.
• The use of BSF meal in aquaculture can contribute to circularity in aquaponic systems.
• BSF-based diets may offer advantages in intensive aquaponics due to lower sodium levels in the recirculating water.