Bait by Laura VanArendonk Baugh. $1.99 from Smashwords.com
They eat us to live. We eat them to live forever. Tomás finds himself consulting on a commercial breeding program for a rare species -- a fish which looks like a mermaid, whose meat is a powerful curative. The corporation with a successful fish farm will command nutrition and pharmaceutical markets. But staff at the facility are dying, and Nature will not wait for research.