Finally I get to see some good ol' pixel art from you! I don't really know a lot about Terraria sprites, but from what I can see here you have some consistency with the rest of the sprites. I suppose these sprites are OK. You seem to be using techniques of anti-aliasing and selective outlining, so the sprites don't look all that bad. It isn't entirely necessary to blow them up to x2 though. My fave out of them is the Barracuda, though I think the area around the teeth has a bit too much of the outline color, and could be cleaned up a bit easily. I'm not really sure about your experience as a spriter so I'm just gonna lay back and see where these Terraria Showcases go before I try overly criticizing them.