Visible Implant Elastomer tagging influences social preferences of zebrafish (Danio rerio)

Abstract

Identification of individuals is a prerequisite in many behavioural studies. Visible Implant Elastomer (VIE) colour tags are a well-established way to mark animals. VIE tagging does not seem to affect individual growth or survival. However, studies verifying their neutrality during social interactions are less common. Here, individual male and female zebrafish Danio rerio were simultaneously given the choice between two shoals, each consisting of six fish. Members of one shoal were uniformly marked with one VIE tag of a given colour, whereas the other shoal was sham-tagged. In total, 10 different colours were used. Test fish spent significantly more time near the tagged shoal (56%) than near the sham-tagged shoal (44%). Tag colour did not significantly influence the preferences. The results highlight the importance of confirming the neutrality of colour tags before using them in behavioural studies. Especially, our study advises caution when using marked and unmarked fish simultaneously.