The Swimming Fish are actually pretty well know in the Korean Pop circle. I think it's because they have a female lead singer and their beats are pretty cheerful for the most part. But, they are at their core, a rock band. They formed in 2003, but didn't put out their first EP until 2006 which was titled Go Away. The band released their first full-length album in 2007, Happy And'Ling. I'll admit, I found them first later in the year with the release of their Christmas album Rockin' Christmas. Obviously it appealed to my senses since I'm obsessed with Christmas music and Korean rock. They were pretty quiet for awhile,but came out on the God of Study OST earlier this year and released an EP this summer as well. They're definitely worth a listen.
For a little Christmas cheer, here is Swimming Fish with a cover of Mariah Carey's All I Want For Christmas Is You:
SF - AIWFCIY by K-RoKer