Work

Running on empty: locomotor compensation preserves fish schooling under hypoxia and informs principles for bioinspired swarms

Year: 2025

Type: article

Abstract: Environmental stressors such as hypoxia challenge the balance between individual physiological performance and the coordination required for collective behaviors like schooling. Here, we investigate how glass catfish ( Kryptopterus vitreolus ) modulate locomotor and group-level behavior across a gradient of oxygen saturation (95%–20%) while swimming steadily at a constant cruising speed. We found that tailbeat frequency decreased significantly with declining oxygen ( p < 0.0001), alongside reductions in wave speed ( p = 0.007). Tailbeat amplitude, by contrast, increased significantly under hypoxia ( p < 0.0001), and posterior segment angles showed a slight, non-significant increase, consistent with modestly greater tail bending. Despite these changes, the Strouhal number remained fairly constant, and waveform topology was conserved. School structure, including nearest-neighbor distance and distance to the center of the school, remained stable across oxygen treatments, but with significant variation across individual schools. A clear behavioral threshold was observed below 25% oxygen saturation, beyond which coordinated schooling deteriorated. These findings demonstrate that glass catfish employ internally coordinated, energetically economical kinematic adjustments to preserve group cohesion under metabolic constraint. This strategy highlights a decentralized mechanism for sustaining collective behavior near physiological limits and offers biologically-grounded insights relevant to energy-aware coordination in bioinspired swarms.

Source: Bioinspiration & Biomimetics

DOI: 10.1088/1748-3190/ae17fd

Authors: Yuchen Gong, Robert Sterling, Xuewei Qi, Fidji Berio, Otar Akanyeti, Valentina Di Santo