I use seaweed selects dried seaweed.also veggieflakes by omega one.your tangs cannot live on seaweed alone.the seaweed is more of a snack not a main course.for main course foods i use emerald entrese frozen food cubes(algae based with mysis shrimp and brine) all my fish love this stuff.my lions will even eat it ,if i dont break up the cube..even though tangs are labeled as herbavour they love meaty foods as well just make sure they have plenty of veggies in there diet and they will stay healthy.giving a variety of foods will provide a balanced diet.tangs should be fed at minimum of twice per day