Greek: azygos = single; Latin: lux = light (pikes have a bright surface).
These trematodes (5.5 cm × 1–5 mm) parasitize the esophagus and the stomach of freshwater fish (pike, trout, and perch). The cilia-less miracidium leaves the egg and penetrates into water snails (e.g., Lymnaea palustris), which thus become first intermediate hosts. Treatment of fish in aquaria can be done by help of Tremazol® (praziquantel in fluid formulation; Fa. Alpha-Biocare, Düsseldorf, Germany).