Movie 1.

Courtship behaviour of WT and double 177 mutant male zebrafish. WT and double mutant males were each crossed 1:1 with WT females (n = 3 pairs). One WT male X WT female sequence is shown, followed by two double mutant male X WT female sequences. In each sequence, a full-speed lateral view is shown first, then slowed to 25%, with annotations indicating the following behaviours: 2) Escorting, 3) Encircling, 4) Quivering, 5) Wrap-around, and 6) Spawning. Chasing is not presented for video brevity, as Chasing and Escorting can occur multiple times before the sequence continues. An overhead view of the Wrap-around behaviour follows, slowed to 10%. WT males participate in all phases of courtship behaviour, resulting in egg release. In the double mutant male courtship sequence 1, males participate in behaviours 2-4, 186 with a clear Wrap-around attempt and bending of the female, but is unable to stimulate egg release. In Sequence 2, the male is shown attempting to Wrap-around the female many times without success, as he is not able to grasp her, due to his pectoral fin defects.