Juvenile sturgeons do not emit sounds under normal maintenance conditions. When fed toxic or semitoxic, juveniles of beluga Huso huso produced a series of wide band pulses. Few signals (0.1 signals/specimen/minute) were produced by fish during the second to the fifth semitoxic food feeding and during the first feeding with toxic food. The number of signals produced by fishes increased considerably up to 2-4 signals/specimen/minute during the sixth semitoxic food feeding and during the second toxic food feeding. Between toxic or semitoxic feeds, juveniles did not produce sound signals. During non-toxic food feeding, juveniles fed just with toxic or semitoxic food did not produce sound signals either. But when oxygen content decreased from 7.8 mg/l to 5.3 mg/l, juveniles fed with toxic or semitoxic food produced 1-3 signals/ specimen/ minute (a series of wide band pulses), while fishes fed with non-toxic food only did not produce any sound signals.