The fish you have will eat a large variety of foods-please offer a wide selection to make sure all their nutritional needs are met.
That roasted seaweed is probably ok, but often foods meant for humans have various additives that we dont want our fish to have.
Let me tell you what most of the folks who have a lot of fish and have been keeping fish for a long time do.
Buy unprocessed seafoods like fish,shrimp,crab, clams etc that you can get at a good price. chop it all up in a food processor (not too fine) Mix in some Zoe or Zoecon and press it into little cubes like the packageed stuff is sold in then freeze it.
Supplement with the dried seaweed products you can buy online that are intended for salt water fish. Add a pelleted food with Garlic as an additive.
OR Buy the multipacks of frozen food that contain 4 different types of food.
Variety is the key to keeping them healthy-and interested in their meals.