I decided to start designing animals for Concept 43, starting with giant ridable fish used much like horses. Round and stout is a common design shape on all the creatures a for the function of being ridden and how they are ridden and used in battle. Each fish has it's unique facial expression, though I tried to give them a cheeky-punk countenance in accordance to Concept 43's general mood.
The four distinct species have emphasis on different tactical attributes such as speed, defense, et cetera. If this is not explicit in their designs, then I have achieved my desired effect!