The Grateful Dead still has its legion of Dead Heads. Jimmy Buffett has his margarita-drinking Parrot Heads. Then there are the fans of New Orleans-based swamp-rockers The Radiators, who are otherwise known as Fish Heads. Following these bayou jammers since they formed back in 1978 (all five original members are still together and rockin'), expect to see some loyal show regulars when the band plays a special SCAN (Stop Child Abuse Now) benefit concert starting at 8 p.m. at Toad's Place Friday, Nov. 21. $20. 648-TOAD.