The role of exercise training in enhancing growth and stress tolerance in silver perch (Bidyanus bidyanus)

Demi L Bestry

Aquaculture is a rapidly expanding industry that is key to meeting global demand for animal-based protein. However, intensifying climate change, particularly heatwaves, has caused mass mortalities in fish farms worldwide. Rising temperatures reduce water oxygen levels, compounding thermal stress with hypoxia and challenging fish survival. To address this, there is growing interest in strategies that improve growth and climate resilience in farmed fish, such as exercise training. Juvenile silver perch (Bidyanus bidyanus) were grown in different water velocities for 12 weeks to encourage natural swimming. The effects of this continuous exercise training on growth, feeding efficiency, thermal and hypoxia tolerance, along with the longevity of potential benefits, were quantified. Fish were maintained in a recirculating aquaculture system and randomly assigned to one of two treatments: exercise, where fish were continuously exercised at a water speed of 2 body lengths s-1, or a control treatment with no water flow (n = 41 fish tank-1, 2 replicate tanks treatment-1). Exercise training resulted in fish that were 25% heavier (final body mass, control: 59.71 ± 0.9 g, exercise: 74.15 ± 0.6 g, mean ± SE) and in better overall body condition (Fulton’s condition factor, K, control: 1.4 ± 0.01, exercise: 1.5 ± 0., 01mean ± SE). Exercised fish did not have a significantly different feed conversion ratio compared than the controls. Thermal tolerance was enhanced in exercised fish, evidenced by a 0.8°C increase in critical thermal maximum compared to controls (control: 37.6 ± 0.06°C, exercise: 38.4 ± 0.12°C, mean ± SE). However, hypoxia tolerance did not differ between treatment groups. After four weeks of detraining, during which exercised fish were placed in tanks with no water flow, the exercise-induced boost in thermal tolerance disappeared, but growth was maintained at a steady rate. These findings suggest that swimming exercise can enhance body condition and thermal tolerance in silver perch, leading to increased climate change resilience and production efficiency for aquaculture farmers. Implementing a structured exercise regime offers a promising, non-invasive, easy-to-implement strategy to enhance fish resilience in aquaculture. By improving body condition and stress tolerance, such approaches support a sustainable farming practice amid the growing challenges of climate change.

The role of exercise training in enhancing growth and stress tolerance in silver perch (Bidyanus bidyanus)

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