These odd looking fishes are know for having limb-like pectoral fins, looking like a sponge or algae-covered rock, sitting very still in a "lie and wait" manner, and having a bait-like structure known as the esca that resembles an enticing food item for attracting small prety and fishes. The length, structure, and morphology of the esca are important diagnostic features for separating the various species. When not used, the esca is tucked against the head. When lost, the esca can be regenerated in a near-identical replacement. Anglers can devour prey the same size as their body due to their stomach's ability to expand. Be careful not to expose them to air when handling as they tend to gulp in air making their stomach expand like a balloon. It usually takes them a while to get rid of the air from their stomach.