Ash's Corphish is a Water-typePokémon owned by Ash. It is the third Pokémon that Ash caught in Hoenn. It's Japanese voice actor is Katsuyuki Konish, and in English it is voiced by Maddie Blaustein (4Kids) and Bill Rogers (TPCi).
Ash first saw Corphish in the episode, "Which Wurmple is Which?", while fishing. However, Corphish ran away. In the episode, "Gone Corphishin' ", a strange figure was moving underground. Brock had a plan to reveal the figure and the plan worked. Ash realized that he caught a same Corphish before on the fishing rod. Ash wanted to capture it again so he used Pikachu. Pikachu was no match for Corphish despite the type advantage. Treecko was sent out instead. Using the method that Ash and his Pokémon practiced, Treecko was able to overcome Corphish's strength and thus, Ash was able to catch it.
Corphish was a surprisingly strong fighter, helping Ash through many battles, including his Gym battle with Juan. In battle Corphish displayed remarkable stamina and in the Hoenn League it endures several Shock Waves, a Shadow Ball, two Body Slams and a Sludge Bomb from a powerful Swalot and still managed to win. It's resilience was displayed again when it battled Tucker's Swampert and Arcanine alongside Ash's Swellow. Corphish was also used in both of Ash's battles with Salon Maiden Anabel.It appeared again in Sinnoh region when Ash asked Professor Oak to sent his Pokémon.Though he didn't take part in any of battle.
It is set to reappear in the Pikachu short airing with the 15th Pokémon movie.