The largest known moray eel is the Slender giant moray , which can reach 4 metres in length . With a maximum length of 11.5 c , the smallest moray is likely the Snyder 's moray ( Anarchias leucurus ) , while the longest species , the slender giant moray ( Strophidon sathete ) reaches up to 4 m. The largest in terms of total mass is the giant moray ( Gymnothorax javanicus ) , which reaches almost 3 m and can weigh over 36 k.