The two wing-shaped fins which comprise Finneon's tail are known not for their role in locomotion, but their appearance; they do little but absorb sunlight in the daytime, but at night they glow brighter than anything else in the sea. Phytoplankton are drawn to the light and potential nourishment, but are quickly gobbled up, for this brightness evolved as a ruse for hunting. But the Finneon enjoy shining all the same, and other pokemon always watch them in awe.
Humans have often employed the Finneon as mobile warning lights, typically using small schools of them to ward ships away from rocks or whirlpools which may be difficult to see in the dark, or to mark contentious maritime borders. Yet Finneon are relatively weak creatures with a strong instinct for self-preservation, so they can at times be manipulated by others. For instance, an unscrupulous nation may seek to alter nautical boundaries by chasing Finneon away with trained Sharpedo, then reposition them on the other side of a disputed maritime resource, provided the stretches of sea look similar enough to fool navigators and law enforcement. Maritime patrols can likewise be warded away from activity one seeks to keep hidden, and many Finneon lights mark not hazards, but pirate lairs.
There are ways to track Finneon activity to try to distinguish genuine warning Finneon from imposters, but many treasure hunters and pirate patrols have drowned after mistaking a genuine hazard warning for one set up to disguise a lair. It is one thing to figure out from the subtle differences in their light and their level of energy when a Finneon is new to an area; another thing to determine why. The hazards of the sea are ever-changing, so not every relocated Finneon is a ruse, and some ruses last a long time.
