Mortality of captive Arapaima gigas (Osteoglossidae) heavily infected with gill monogenean Dawestrema cycloancistrium.
Dawestrema cycloancistrium was found to be responsible for the deaths of 8 Arapaima gigas in a public aquarium in Denmark. Gills were heavily infested with several hundreds of monogeneans. the gill tissue was severely affected by the infection and showed extended necrotic areas, inflammatory reactions and destroyed secondary lamellae. Two of the fishes came from Hong Kong and 6 were newly imported hatchery reared fish from Brazil. All became lethargic and died within 2 weeks.