The cellular structure of seaweeds comprises indigestible fibres or complex polysaccharides, which are used as thickening additives or gelling agents in a range of processed foods and in cosmetics, pharmaceuticals, nutraceuticals and other industries. To date, only a handful of seaweed species have been used commercially as animal feed additives. Two main reasons underpin the use of seaweeds as dietary additives are to bolster the immune system of farmed animals and to improve their productivity and meat quality. Southeast Asia could play a significant role in the production of tropical seaweeds for animal feeds. Due to the vast number of seaweed species, novel seaweed additives, with the potential for animal production, are being discovered.