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| Sound produced | yes, active sound production |
| Type of sound produced | knocks & chewing sounds |
| Sound production organ | pharyngeal teeth & swim bladder in young, mostly swim bladder in old (teeth are numerous in young, but deciduous with age) |
| Sound mechanism | not specified, but probably pharyngeal teeth stridulation amplified by adjacent swim bladder and swim bladder vibration by muscle contraction |
| Behavioural context | under duress (manual & electric stimulation), escape knocks when avoiding hand, chewing sounds during feeding |
| Reference | Fish, M.P. and W.H. Mowbray, 1970 |
| Remark | recorded with bandpass filter: 30 -1200 Hz, recording amplified by 6 dB |