Differential responses of male and female red swordtails to chemical alarm cues

Male and female red swordtails Xiphophorus helleri exposed in the laboratory to sword,tail skin, extract, fathead minnow Pimephales promelas skin extract and distilled water, significantly decreased activity in response to conspecific skin extract compared to minnow skin extract or distilled water. Moreover, males and females responded differentially to conspecific skin extract. Males tended to occupy the top compartment of the tank, whereas females tended to occupy the bottom compartment and seek shelter more. In a second experiment swordtails reduced activity, significantly more in response to swordtail skin extract compared to closely related guppy Poecilia reticulata skin extract, minnow skin extract or distilled water. Swordtails also reduced activity significantly more to guppy skin extract compared to minnow skin and distilled water. However, males and females did not respond differentially to guppy skin extract. This suggests that chemical alarm cues are partially conserved within the Poeciliidae, but the level of response is of lower intensity to heterospecific skin extracts. (C) 2001 The Fisheries Society of the British Isles.