Well, I certainly can’t turn down a request like this, especially when I agree it’s unfortunate that finneon and lumineon seem to be overshadowed in the fish pokémon enthusiast communities by the likes of goldeen, feebas, and magikarp.
….
And yes, there are, in fact, fish pokémon enthusiast communities.
Finneon
The Wing Fish Pokémon
Type: Water
Official Registration #: 456
Entry: A small, neon tetra-like pokémon first discovered in the waters of Sinnoh. The pink designs along the sides of its body and within its fins contain specialized cells that can store sunlight and release it at certain intervals (usually whenever the subject is attempting to attract prey or a mate). Additionally, as it swims, finneon fan out its double tail fins, and this, combined with the beauty of the light it emits, have earned it the nickname “beautifly of the sea.” This, of course, means finneon is the second fish-like pokémon whose name calls to mind another creature, but unlike in lanturn’s case, the pokémon involved in the comparison couldn’t care less, largely because finneon’s attempts at flight generally leave actual beautifly rather unimpressed.
Lumineon
The Neon Pokémon
Type: Water
Official Registration #: 457
Entry: The evolved form of finneon, by battle experience. Using its pectoral fins, this butterflyfish-like pokémon crawls across the ocean floor to avoid predators. As it crawls, it lights up patterns on its large, billowing tail fins to attract prey. In this manner, it competes with lanturn, who uses similar mechanisms to hunt, dwells in the same general habitat, and is also in a pokémon family frequently compared to a completely different creature. However, given the fact that lanturn can emit powerful electrical attacks and the fact that lumineon boasts no resistance to said electrical attacks whatsoever, lanturn are generally about as impressed with lumineon as beautifly are with finneon. Which is to say, not at all, regardless of how much the poor things try.
The Pokédex According to Bill 