The main body is a foam egg used in flower arranging and the tail is a piece of straightened paper clip with the body/tail shape built up from two-part epoxy and sanded to shape before the fins were added from 'green stuff'.
Painting is acrylic paints over a filler and PVA glue base, to add bulk. The colour scheme is as the I SEE LEAD PEOPLE BLOG (details below).
A full description of this particular Aerofauna is taken from Aerofauna of Secundus part one, see;
The Yellow Bow. Filling a niche analogous to terrestrial dolphins or smaller whales, the Yellow Bow, named so for the yellow spot on the front of its body, is a relatively harmless creature. Sporting the common trailing tail tendril it utilizes a pectoral flange to propel itself at great speeds.Yellow Bows are not predators but instead strain off massive amounts of cloud-borne algae common in the upper reaches of the sky. When threatened or during mating season, they can become quite agitated and dangerous, attacking anything they perceive as a threat natural or man-made alike.In addition to its characteristic yellow front spot, the Yellow Bow is distinguished by its sky blue color with grey and white banding along their sides. Each of their three bands is marked by three bio-luminescent spots which it uses for communication.
PS. Thanks to Eli for all the inspiration.