Nile Tilapia and Gilthead Seabream Dietary Self-Selection of Alternative Feeds with Spirulina and Quinoa

Abstract

Abstract Classical assessments of new fish feeds are anthropocentric, focusing on growth. Although this methodology is accurate, it does not consider the fish’ perspective. This study aimed to investigate the behavioural responses and feed preferences of Nile tilapia - Oreochromis niloticus and gilthead seabream - Sparus aurata, in two self-selection trials (self-feeders and diet encapsulation). Using self-feeders, both species were offered three feeds: a control (PD) and two diets (ORG1 and ORG2) containing non-conventional ingredients, including spirulina (Spirulina platensis) and quinoa (Chenopodium quinoa). Three groups of tilapia with an average weight of 163.0 g ± 4.3 g (mean ± SD) and four groups of seabreams with 174.7 g ± 27.0 g were tested. To investigate the role of olfactory factors in dietary selection, three other diets were encapsulated and offered to tilapia: Diet A, a purified feed, Diet B that contained predominantly spirulina and Diet C which had a mixture of spirulina and quinoa. Seven individual tilapia of 331.9 g ± 31.4 g were used. Using self-feeders, tilapia exhibited a preference for ORG2 (46.5%), which was influenced by the sensory properties of feeds and post-ingestion signals, as their choice for ORG2 persisted during diet encapsulation using Diet C, which was also formulated with quinoa and spirulina. Seabream did not show a preference for any feed. These findings highlight the effectiveness of self-selection experiments in allowing fish to express their feeding behaviour and preferences. Therefore, this approach should be considered in the initial screening and design of new aquaculture feeds and ingredients.