Mass moralities were encountered in Perca fluviatilis from Axwell Park Pond in Northumberland. It was know from a previous study (Afi 1984) that this population has a high incidence of “liver cysts”. At the time of this morality fish had numerous “cysts” in and on the liver. the kidneys. https://fitnessgravesyardes.shop/product-category/left-bearing-house/