How does food enrichment and the presence of visitors affect the behaviour of two species of freshwater fish in a public aquarium? (2025)

Silva, A. A., Azevedo, C. S. de, Cipreste, C. F. et al.

Abstract

Food-based environmental enrichment (EE) is a valuable strategy for stimulating foraging behaviour in fish under human care, as it increases the challenge of food acquisition and encourages prolonged engagement in this activity. Curimbas (Prochilodus argenteus) and pacus (Myleus micans) are fish species for which ex situ maintenance has become an important conservation measure. In this context, providing EE is essential to ensure high welfare standards. This study aimed to assess the effects of food enrichment on the behaviour of these two endemic species from the São Francisco River basin in Brazil. Behavioural data were collected across three experimental phases, including baseline, enrichment, and post-enrichment. Slow-dissolving food items known as “acorns” were introduced during the enrichment phase. Both species exhibited a marked reduction in inactivity throughout the study. For curimbas, the enrichment phase was associated with increased foraging, elevated agonistic interactions, and greater use of specific tank areas. Among pacus, inactivity significantly declined during the enrichment period. Additionally, the presence of visitors influenced behavioural patterns, promoting foraging activity while reducing inactivity and interactions with the enrichment device. These findings reinforce the value of incorporating environmental enrichment to promote the welfare of freshwater fish in public aquariums.