The observation of distinct locomotor behaviour presented by the different zebrafish embryos is consistent with the findings of previous studies. From 17 hpf, zebrafish embryos demonstrate spontaneous tail coiling by contracting the sides of its tail, a form of specialised locomotor behaviour activity (Brustein et al., 2003). Spontaneous tail coiling is not myogenic but arises from the innervation of functional motorneurons, which are situated in the spinal cord, and the frequency of the activity is most enhanced in 19 hpf embryos (Saint-Amant and Drapeau, 1998). Supraspinal input is not depended upon and neurotransmitters such as glutamate and glycine do not regulate this form of locomotor behaviour (Saint-Amant and Drapeau, 2001 cited in Downes and Granato, 2005).…