Flying Gurnard

One species in three tiers: the Atlantic Flying Gurnard (Dactylopterus volitans). It walks across the sand on stiffened pelvic rays and, when it decides to, opens a pair of pectoral fins wide enough to look like a different animal entirely. Nothing else in the trade moves like it, which is the whole reason people want one.

Feeding is where they fail. A gurnard forages slowly along the bottom and loses every race to a tang or a wrasse, so it wants a wide, open sandbed and food put down for it directly. If your tank is rock wall to rock wall with fast eaters, skip it. Buying it already eating removes most of the risk.