The present research is a first attempt for the use of alga Gracilaria gracilis as a source of preservative compounds to be applied during the chilled storage of fish. For it, a combination of ethanolic and aqueous extracts of this edible seaweed were included in the icing medium employed for the chilling storage of hake (Merluccius merluccius). Chemical and sensory analyses related to quality loss were carried out in fish throughout 9-day storage. Three different alga concentrations were tested and compared to an icing control (traditional ice). As a result, an inhibitory effect (p<0.05) on lipid oxidation development (tertiary oxidation compounds) and microbial activity (trimethylamine formation) was observed in fish corresponding to batches including the two most concentrated alga conditions. However, a definite effect on lipid hydrolysis development (free fatty acids formation) could not be implied (p>0.05). Concerning sensory analysis, samples from the same two batches revealed a higher acceptance (p<0.05) than control; this difference was based on the evaluation of various descriptors such as skin, external odour, raw flesh odour and cooked flesh odour. On the basis of the presence of antioxidant and antimicrobial molecules, a profitable effect on quality retention of chilled hake is concluded by including G. gracilis extracts in the icing system.