Millions of ornamental fish species are reared in captivity for use in commercial settings including aquaculture, in hobbyists’ aquaria and as models for scientific research. These fish are exposed to environmental stressors which may negatively impact their welfare, including poor water quality, inappropriate stocking densities, disease exposure or injury. These stressors can detrimentally affect fish, influencing their physiology and behaviour and decreasing their market value. This highlights the need to house fish in stable environmental conditions that maximise their welfare. The aim of this project is to use metabolomics to non-invasively detect changes in fish stress levels. Once suitable metabolites are identified, we will employ quantitative analytical chemistry to analyse them and establish novel biomarkers for stress.
Measuring fish health and welfare can be challenging because the majority of popular ornamental fish species have a small body size; and the sampling techniques used in aquaculture or laboratories are highly invasive. Current readouts of welfare include measuring hormone levels and behaviour, but these approaches may require blood or tissue samples to be collected leading to stress. Our recent research has focussed on developing a refined non-invasive replacement method to measure stress markers in DNA samples. We adapted a protocol to collect and purify DNA from skin mucus samples collected using a small rayon-tipped swab. We found that skin swabbing was a refined technique for DNA collection compared to a standard fin clipping procedure. We were also able to detect hundreds of metabolites in mucus samples collected from goldfish, an important species in the aquatic pet trade. In addition, chasing fish with a net induced a stress response that we detected as changes in mucus metabolite levels as the fish recovered over time.
In this project, we will identify novel biomarkers of stress with the aim of developing a non-invasive test for fish health and welfare. We will: 1) establish a sampling protocol and extend our preliminary data by using larger sample sizes; 2) compare different stressors commonly encountered by aquaculture, ornamental or laboratory fish (including simulated transport, net restraint, and changes in housing and environmental conditions) to determine if there is a universal stress marker; 3) develop a standalone test to non-invasively detect changes in fish stress levels based upon metabolite markers identified using metabolomics and analytical chemistry methodologies; 4) utilise the identified biomarker to assess the impact of commercial products (i.e. water conditioners and/or diet) on fish health and welfare.
Primary supervisor: Professor Don Jones, University of Leicester
Non-academic partner: Dr Donna Snellgrove, Mars Petcare UK
Candidates are encouraged to contact Professor Don Jones to discuss the project before applying if they wish to.
Deadline: 04 January 2024
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