[Tumour occurrence of minnow Phoxinys phoxinus (L.) from the North Dvina and Pechora River Basins].

Tumours occurrence of minnow and tumour parameters are found to be greatest at the end of June--the first part of July. Black tumours give metastases, while gray tumours are separated from the neighboring tissue by a capsule. The stroma of the tumour is pierced through by fungal hyphae of Fusarium solani (Mart.) App. et Wr. The minnow living the first year (the end of it) and the second year (the beginning of it) suffers tumours more frequently. The minnow taken from the Saitanovka river estuary (the cordon place, abundant in Equisetum, which is the motorboats anchorage) was found to be most affected by tumours.