As described by Beebe, this fish had brownish skin and a roundish body with small pectoral fins and large eyes. Its most notable feature was its five lines of purple and yellow bioluminescent photophores on either side.
The constellation fish was seen by Beebe during a 1932 dive off Bermuda, at a depth of 1900 feet:
- "A small school of luminous fish had just passed, when, fortunately at a moment of suspension, came a new and gorgeous creature. I yelled for continuance of the stop, which was at 1900 feet, and began to absorb what I saw; a fish almost round, with long, moderately high, continuous, vertical fins; a big eye, medium mouth, and small pectoral fins. The skin was decidedly brownish. We swung around a few degrees to port, bringing the fish into the dark blue penumbra of the beam, and then I saw its real beauty. Along the sides of the body were five unbelievably beautiful lines of light, one equatorial, with two curved ones above and two below. Each line was composed of a series of large, pale yellow lights, and every one of these was surrounded by a semicircle of very small, but intensely purple photophores.
- "The fish turned slowly and, head on, showed a narrow profile. If It were at the surface and without lights I should, without question, have called it a butterflyfish (Cbcetodon) or a surgeonfish (Acanthunis). But this glowing creature was assuredly neither, unless a distant relation, adapted for life at three hundred fathoms. My name for it is Bathysidus pentagrainfmis, the Five-lined Constellation fish. In my memory it will live throughout the rest of my life as one of the loveliest things I have ever seen."
Carl Hubbs believed Beebe had simply seen a mass of jellyfish distorted by his own breath on the bathysphere's porthole.