Fish:
I have a single fish, a male
Synchiropus picturatus (spotted mandarin). He was eating a little frozen brine at the LFS, but I trained him onto frozen mysis over time. In this small tank, the fish is not shy at all, and he even swims in the water column.
Recently, he had a fall out with the powerhead's outlet. As a result, he will pose aggressively towards it and will peck at it every time he swims by.