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While soundscapes shape the structure and function of auditory systems over evolutionary timescales, there is limited information regarding the adaptation of wild fish populations to their natural acoustic environments. This is particularly relevant for freshwater ecosystems, which are extremely diverse and face escalating pressures from human activities and associated noise pollution. The Siamese fighting fish Betta splendens is one of the most important cultured species in the global ornamental fish market and is increasingly recognized as a model organism for genetics and behavioural studies. This air-breathing species (Anabantoidei), characterized by the presence of a suprabranchial labyrinth organ that enhances auditory sensitivity, is native to Southeast Asia and inhabits low flow freshwater ecosystems that are increasingly threatened due to habitat destruction and pollution. We characterized the underwater soundscape, along with various ecological parameters, across five marshland habitats of B. splendens, from lentic waterbodies to small canals near a lake in Chiang Rai province (Thailand). All habitats exhibited common traits of low dissolved oxygen and dense herbaceous vegetation. Soundscapes were relatively quiet with Sound Pressure Level (SPL) around 102-105 dB re 1 mu Pa and most spectral energy below 1,000 Hz. Sound recordings captured diverse biological sounds, including potential fish vocalizations, but primarily insect sounds. Hearing thresholds were determined using auditory evoked potential (AEP) recordings, revealing best hearing range within 100-400 Hz. Males exhibited lower hearing thresholds than females at 400 and 600 Hz. This low-frequency tuning highlights the potential susceptibility of B. splendens to anthropogenic noise activities. This study provides first characterization of the auditory sensitivity and natural soundscape of B. splendens, establishing an important ground for future hearing research in this species. The information provided on the auditory sensory adaptation of B. splendens emphasizes the importance of preserving quiet soundscapes from lentic freshwater ecosystems.
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<jats:title>ABSTRACT</jats:title><jats:p>As intensive aquaculture continues to develop, substantial investments have been made in equipment to sustain high‐density farming. However, this has resulted in elevated noise levels within these aquaculture environments, particularly below 2000 Hz, matching the hearing range of most cultured fish species. Fish under noise conditions may experience hearing loss and physiological stress, which can negatively affect their growth, foraging efficiency, reproductive success, and increase their susceptibility to diseases. These adverse effects compromise the welfare of cultured fish, potentially decreasing production quality and increasing mortality rates. Despite these notable effects, the understanding and management of noise conditions in aquaculture systems lag behind other environmental parameters in terms of recognition and control. In this review, we cover the fundamentals of fish auditory systems, the hearing range of key cultured fish species, and the most common noise sources and levels prevalent in current intensive aquaculture systems. Additionally, we examine recent discoveries on the effects of anthropogenic noise on fish hearing, physiological responses, and behavior. Finally, we provide strategies for noise monitoring and management in the aquaculture industry, while also highlighting open questions for future research. Our goal is to assist researchers and practitioners in comprehending underwater noise and its effects on cultured fish species, providing a valuable resource for promoting the healthy and sustainable development of intensive aquaculture.</jats:p>