BORED FISH by Austin L.
Austin's "Bored Fish" tessellation is a reflection (flip, mirror, glide) tessellation. You can tell it's a reflection tessellation because each row of fish is repeated in the row below it, except the row below it is facing the other way and not upside-down..
This is also a two-theme tessellation, in this case fish + seaweed.
Here's an artistic point to consider: Is this a tessellation? Well, if the fish are shaped kinda weird, then the answer is "yes". If the fish are normal shaped, but hiding their tummies and tails behind other fish, then the answer is "no, that's not a tessellation." The shapes in tessellations do not overlap.
Fish, by the way, are a good and popular theme, if you make a tessellation. They're a good choice because their bodies and fins are bendy this-way-and-that, and they come in a startling variety of body shapes. Here's a short, fun essay about why fish are a great theme for tessellation.