Microalgae-blend tilapia feed eliminates fishmeal and fish oil, improves growth, and is cost viable

Abstract

Aquafeed manufacturers have reduced, but not fully eliminated, fishmeal and fish oil and are seeking cost competitive replacements. We combined two commercially available microalgae, to produce a high-performing fish-free feed for Nile tilapia (Oreochromis niloticus)—the world’s second largest group of farmed fish. We substituted protein-rich defatted biomass of Nannochloropsis oculata (leftover after oil extraction for nutraceuticals) for fishmeal and whole cells of docosahexaenoic acid (DHA)-rich Schizochytrium sp. as substitute for fish oil. We found significantly better (p < 0.05) growth, weight gain, specific growth rate, and best (but not significantly different) feed conversion ratio using the fish-free feed compared with the reference diet. Fish-free feed also yielded higher (p < 0.05) fillet lipid, DHA, and protein content (but not significantly different). Furthermore, fish-free feed had the highest degree of in-vitro protein hydrolysis and protein digestibility. The median economic conversion ratio of the fish-free feed ($0.95/kg tilapia) was less than the reference diet ($1.03/kg tilapia), though the median feed cost ($0.68/kg feed) was slightly greater than that of the reference feed ($0.64/kg feed) (p < 0.05). Our work is a step toward eliminating reliance on fishmeal and fish oil with evidence of a cost-competitive microalgae-based tilapia feed that improves growth metrics and the nutritional quality of farmed fish.

Towards Environmental Sustainability in Marine Finfish Aquaculture

“…It is estimated that if microalgae were used as fishmeal replacement, the effect would be to remove 30% of the fishing pressure thereby helping to conserve marine ecosystems (Beal et al, 2018). Algae may substitute fish oil, be viable and even improve growth of farmed fish so it should be considered to reduce harvesting fish for fishmeal (Sarker et al, 2020).…”

Microalgae: Potential for Bioeconomy in Food Systems

“…Salmon and carp fed with Nanofrustulum sp., Tetraselmis sp., and Haematococcus pluvialis, and tilapia fed with N. oculata, and Schizochytrium sp. showed improved health and higher nutritional value compared to the meat [82,[84][85][86].…”

“…The implementation of microalgae in fish farming is an environmentally friendly alternative to the non-sustainable fishmeal and fish oil-based feeds currently used. Microalgae have been successfully tested in salmon, trout, tilapia, ornamental fish, and crustaceans [51,82]. In farmed shrimp, feeding with T. chuii, Dunaliella sp., A. platensis, Hypnea cervicornis, and Cryptonemia crenulata improved both immunity and production [52,83].…”

Editorial: Chemically Mediated Interactions Between Marine Macrophytes and Microbes

“…Marine macrophytes and phytoplankton are dominant primary producers in marine ecosystems worldwide (e.g., Behrenfeld et al, 2001). They produce oxygen and form the base of food webs, are ecosystem engineers, and provide ecologically and economically valuable functions and services (e.g., Holdt and Kraan, 2011;Sarker et al, 2020;review by Pierella Karlusich et al, 2020). Phytoplankton and macrophytes are not single isolated entities but establish intimate relationships between them as well as with non-photosynthetic microbes (including bacteria, fungi, viruses) forming holobionts.…”