Under The Water And Mutated Fishes is a Manga/Manhwa/Manhua in english language, Horror series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

After a heavy downpour, the whole city became flooded. The fish went through a mutation, its intelligence became closer and closer to human...facing off these evolved fish, will we survive?