Study of behavioral responses of crayfish (Astacus leptodactylus) to free amino acids

For many aquatic animals olfactory has an important role in food searching and intake. Amino acids are the large group of olfactory stimulants in feeding behavior of aquatic organism. The aim of the study was to determine the olfactory preference in crayfish (Astacus leptodactylus). Crayfish juveniles (6 to 8cm L) were exposed to 20 amino acids, and two positive and negative controls, in laboratory condition. Experiments were carried out in 6 replicates. In the qualitative evaluation of crayfishs responses, Aspargine and Sistine stimulated a significant and obvious feeding reaction. The quantitative evaluation confirmed the effect of Asparagine but showed weak response for Sistine. Phenylalanine, threonine, tyrosine, methionine, and lysine promoted low positive response. The quantitative evaluation verified this result except for tyrosine and phenylalanine. Other amino acids didn’t show considerable attractive effects on feeding behavior. The quantitative evaluation confirming the results of pervious observation showed the well apparent response for glycine and thriptophan. The responses for aspartic acid, serine, acid glutamic and proline were sufficiently positive. According to the results asparagine could be considered as a suitable appellant for Astacus leptodactylus.