Brown algae, dead fish??!!

[<3thefish]

The last few days Ive notices brown algae starting up, not a lot but noticeable. This morning when I woke up my tang was dead. He hadn;t been acting sick . He was eating fine but was not swiming as much, but not anything to worry about becasue he was eating (so i thought) None of the other fish are acting funny. Is the brown algae meaing my tank is cycling again, its been setup for 6 months. and ifs its cycling again is that why the tang died???

PLEASE HELP