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Artist badge = college gift! I hope you like it kiddo. Seriously, congratulations and thank you for your hard work and great attitude all of this time.
When pom and I were looking over the bunny we mentioned the old back is ok except for ears. Still needs overall reshading though. You can feel free to redo it all if you want, your call.
I generally have little interest in CAP, but I've been looking at the art submissions thread from time to time and want to say that, while I think most of the entries aren't very believable as Pokemon, imo your mermaid design is both convincing and attractive in itself. I would suggest playing with the colour scheme to get something more bold and fiery, and doing a really kickass final picture for it.