William, your co-worker, was standing next to the water cooler, sipping a cup of cold water.

He was next to the water cooler.

As if he couldn't live without it.

Like he has a fish tail and gills that compelled him to go near water.

But of course that's just a metaphor. He's not actually a fish.

It's impossible for a fish to turn Human and merman/mermaids cannot turn into humans.

William was murmuring something while watching the fish swim around in the office's fishtank.