Title: Growth in response to sustained swimming in young montezumae swordtails,<b><i>Xiphophorus montezumae</i></b>
Abstract: Abstract This study tested the effect of sustained swimming on growth, ingestion rate, and morphology of juvenile montezumae swordtails (Xiphophorus montezumae). Because montezumae swordtails inhabit running freshwater systems, it was expected that moderate exercise would increase feeding and growth rates, promoting also the hydrodynamic form of the fish. Experimental groups were subjected to different levels of sustained exercise by being forced to swim against water currents at four different velocities (0, 4.1, 7.8, and 12.9 cm/s). The results showed that growth-rate decrease in fish forced to swim, while the increase in exercise did not modify the ingestion rate. Thus, it is likely that the extra energy expenditure associated with the swimming cost was not compensated by an increase in food ingestion. Sustained exercise increased the fineness ratio towards a more hydrodynamic form. Morphological traits linked with minimum drag, such as caudal peduncle depth and amplitude of the caudal fin were not modified. Our results suggest that water velocity has an important role determining the physiology and, to a lesser extent, the morphology of young montezumae swordtails. Keywords: exercisefeedinggrowth plasticityswimmingtrainingfishswordtail Xiphophorus montezumae Acknowledgements We thank Karla Kruesi for helpful input during the experiments and for useful comments on drafts of the manuscript. We also thank Maribel Badillo for technical assistance during the experiments. We thank Jesus Saenz for support on the construction of the experimental systems. Thanks to Lucille Diamond for editing of this English language text.
Publication Year: 2008
Publication Date: 2008-03-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 12
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