The amia is found in some medieval encyclopedias.It is a rock fish which has a colored skin, though the authorities disagree about the color. Pliny the Elder says it is sulfur-colored when in the water but colored other fish out of the water. Isidore of Seville says it has purple stripes on its sides. Thomas of Cantimpré says that it has reddish stripes and that its skin has multiple colors like silk cloth, and that it has a stone inside. It is a fish that can only be caught with a hook.

The amia may be the bonito, bluefish or mackerel.