It's a famed Chinese Algae Eater, now at 6cm. I've had it for months with my platies and it's never touched them - they actually bully the loach, especially when there's an algae wafer. Vicious little girls I'm surprised at all the bad press they get - they don't like other CAEs (my two chase each other) but they don't bother other fish, even in a small tank
LFS has flags and minnows, and so far the flags look like the best option. Anyone kept them?