This article about guppy sex strongly suggests choices, and thinking:-Bierbach's results are best summarised in the title of the journal article: "Casanovas are liars". The results indicate that male poeciliids are indeed tricksters: males showed significant "audience effects" in nine of the ten species that were tested. There was a positive correlation between level of sexual activity and the likelihood that a male fish would show audience effects in his mate choices. However, the analyses show correlation, not causation. Every reason to keep studying guppy sex.- Read more at: http://phys.org/news/2013-09-guppies-choice-rivals.html#jCp