Seaking is a large, orange, fish-like Pokémon. It has billowing caudal and pectoral fins, all of which are white specked with black. However, its dorsal fin is pure white and rigid. It has round, dark eyes, prominent pink lips, and small fangs, as well as a horn in the center of its forehead. Females have smaller horns than males.
Seaking is a very powerful swimmer that is found in rivers and streams. It can not only swim against a river's current, but can travel up waterfalls. In the autumn spawning season, it travels upriver, where male Seaking, grown fattier and more vibrant in color, engage in elaborate dances to court females. Seaking uses its powerful horn to bore holes in riverbed boulders in order to shelter its Eggs from water currents. A mated pair takes turns patrolling around their new nest for roughly a month, and defends it with their lives.
Ash, Misty, and Professor Oak have owned Seaking in the past, though Ash and Misty released theirs only a short time after capturing it, due to the rules of the competition in Hook, Line, and Stinker, and Professor Oak's Seaking was mentioned in the dub only.
Juan also owns a Seaking, which was used in a Gym battle against Ash in The Great Eight Fate!. Juan's Seaking was able to block Electric attacks with Horn Drill and send them back at its opponent.
In the autumn, Seaking males can be seen performing courtship dances in riverbeds to woo females. During this season, this Pokémon's body coloration is at its most beautiful.
Seaking is very protective of its eggs. The male and female will take turns patrolling around their nest and eggs. The guarding of eggs by these Pokémon goes on for over a month.
In Gold, Silver, and Crystal Versions, it appears that Seaking was originally set to learn Supersonic as one of its three starting moves. However, the game programmers made an error and filled the third data slot with Tail Whip, so Seaking ended up with two starting moves instead.
Origin
It seems to be based on a species of goldfish known as Azuma Nishiki (東錦), bearing a similar coloration to Shubunkin goldfish. The horn part may be based on Matsya, an avatar that the Hindu god Vishnu assumed, which is sometimes depicted as a fish with a horn.
Name origin
Seaking is a combination of sea and king. Additionally, it may be a pun on "sinking".
Azumao may be based on 小豆鱒 azukimasu (rock cod) and 魔王 ma-ō (devil king). It may also be taken to literally mean 東王 azuma-ō (east king). Additionally, 東錦 azuma nishiki is a kind of goldfish and could be combined with 王 ou (king), as a compliment to Goldeen's "queenliness".