ive had good success with fish that have ich using the Omega One Flake for Marine fish with garlic. .. i use it as a daily staple along with other foods but i make sure they get this daily. its like their multi vitamin all my fish are fat and happy.
also for tangs imo its best to have cleaner fish and shrimp and i feed small ammounts of nori daily instead of 1 full sheet every few days i do 1/3 sheet daily. but just make sure they are getting plenty of algae to eat whether its daily or every few days. i use the Omega One super veggie red seadweed and even my chromis love this stuff and even pick at it off the clip.
also for tangs imo its best to have cleaner fish and shrimp and i feed small ammounts of nori daily instead of 1 full sheet every few days i do 1/3 sheet daily. but just make sure they are getting plenty of algae to eat whether its daily or every few days. i use the Omega One super veggie red seadweed and even my chromis love this stuff and even pick at it off the clip.