Also wondering this. The article mentions the difficult problem of scaling up red algae farming - could the active ingredient not be synthesized commercially and added to feed that way?

edit, from Wikipedia: "The substance may be hazardous to the environment, and special attention should be given to aquatic organisms. Its volatility and environmental persistence makes bromoform's release, either as liquid or vapor, strongly inadvisable. ... Bromoform is a confirmed animal carcinogen" Although I presume the bromoform binds to the enzymes and/or otherwise reacts in the stomach, as usual there are pros and cons associated with this sort of thing