The importance of a suitable diet for reproduction has been recognized as one of the major factors in ornamental aquaculture. In seahorses, mysids have been described as preys in the wild. Also, Artemia has been usually employed for rearing fish, including syngnathids. Therefore, the aim of this work was to evaluate the effect of these live preys on the spawning quality of Hippocampus hippocampus. After 108 d, no differences were found in adults concerning all biological parameters evaluated, but broodstock fed on mysids showed better results than Artemia regarding number of spawning events (12 vs. 3), brood sizes (233.50 ± 59.04 vs. 68.00 ± 57.97 juveniles), and newborn seahorses standard length (10.61 ± 0.64 vs. 8.75 ± 1.32 mm). The better nutritional quality of mysids, overall in Docosahexanoic acid, could be one of the main responsible factors. However, mysids stock is conditioned by natural catches and rearing techniques are little known. Another alternative would be to combine them with Artemia in mixed diet. Further research must be done concerning mysids breeding techniques to delineate their employment as a sustainable prey for seahorse aquaculture. This trial showed for the first time the effect of mysids to enhance reproduction efficiency in H. hippocampus.