The Delancey and Essex Street Station is home to the J, M, Z, and F Trains, and also this colorful glass mosaic mural of two fish, which appear to be swimming on the surface of the water. Fun!
With minimal Googling, I discovered that the mural is called Shad Crossing, Delancey Orchard (2004) by artist Ming Fay. For the backstory, let’s go to Yelp Reviewer Tina C. from Queens, who writes:
Glass mosaics on platform and mezzanine walls symbolizes the the liveliness of the once thriving fishing marketplace in this storied Lower East Side community. Aquatic images are a metaphor for “crossing” in a glass mosaic mural on the Brooklyn-bound platform, inspired by the prominent DeLancey family’s eighteenth century farm, which stretched from the East River to the Hudson River. The farm’s cherry orchard was located where Orchard Street stands and is memorialized with radiant cherry trees on the Manhattan-bound platform.
The larger mural is adjacent to this underground directive (above) , but on the platform for the Brooklyn Bound F, you will also find these small tile mosaic Fish Heads at random intervals along the wall.