Body tactile stimulation and fish welfare effects on aggressive behavior, brain monoamines, and productive performance

• Grant number: 23/02306-1
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2023
• End date: January 31, 2026
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Eliane Gonçalves de Freitas
• Grantee: Eliane Gonçalves de Freitas
• Host Institution: Instituto de Biociências, Letras e Ciências Exatas (IBILCE). Universidade Estadual Paulista (UNESP). Campus de São José do Rio Preto. São José do Rio Preto , SP, Brazil
• Associated researchers: Marta Sofia Candeias Soares
• Associated scholarship(s): 24/18073-9 - Automatic recording system to test the effects of free choice by tactile stimulation on welfare in Nile tilapia, BP.TT; 23/09880-5 - Effect of free choice by tactile stimulation on aggressiveness and brain monoamine levels in Nile tilapia, Oreochromis niloticus (L.), BP.TT

Abstract

This project aims to apply body tactile stimulation (like human touch or therapeutic massage) to improve fish welfare. For this, we developed an apparatus made of plastic sticks containing silicone bristles on their sides, which are lined up in the center of the aquarium and through which the fish cross, receiving tactile stimulation. In previous studies, we observed a reduction in aggressiveness and an increase in growth in Nile tilapia, showing that this is a promising tool for improving fish welfare. However, this is a new thematic area, whose mechanisms, and effects to different species are still poorly understood. One of the possible mechanisms for reducing aggression in vertebrates is the increase in brain monoamines, such as dopamine and serotonin. Here, we will test the effects of tactile stimulation on aggressiveness, social stress, and monoamines in Nile tilapia, Oreochromis niloticus, in a context of free choice to access stimulation (study 1); in angelfish, Pterophyllum scalare, and betta fish, Betta splendens (study 2), and in the appeasement behavior of the pearl cichlid Geophagus iporangensis (study 3). The animals will be assigned to treatments with or without stimulation (control) for 21 to 25 days. We will evaluate aggressive interactions, plasma cortisol, blood glucose, dopamine, and brain serotonin. In all cases, tactile stimulation is expected to improve welfare by raising the levels of these monoamines, as well as improving productive performance due to the reduction in energy expenditure from fights and social stress. This proposal is innovative and is in line with the international scientific scenario. It is also likely to generate low-cost technology that may be potentially used to mitigate the negative impacts of the aquaculture rearing system and management, as well as to add value to the aquaculture trade. (AU)