Small, benthic bony fishes constitute over 90% of the marbled electric ray's diet by weight; these include gobies, hake, sea bass, mullets, jack mackerel, sea breams, goatfish, damselfish, wrasses, conger eels, and flatfish. Cephalopods such as European squid ("Loligo vulgaris") and elegant cuttlefish ("Sepia elegans") are a minor secondary food source. There is a single record of an individual that had swallowed a penaeid prawn, "Penaeus kerathurus", and a study of captive rays found that they reject live "Macropodia" crabs. Off southern France, by far the most important prey species is the leaping mullet ("Liza saliens"). Food items are swallowed whole; there is a record of a ray long that had consumed a three-bearded rockling ("Gaidropsarus vulgaris") long.