The aim of this study was to determine the effect of fish meal and mineral-vitamin premix, supplementing organic diets, on the performance of pigs and some meat and blood characteristics. The experiment was conducted on an organic pig fattening farm. The study involved 120 pigs with an approximate 25 kg body weight. Animals were divided into 3 groups, kept in pens, 10 animals each. Group I (control) animals were fed with plant feedstuffs of organic origin. Diets for group II and III were enriched with fish meal or fish meal and vitamin-mineral premix, respectively. The experiment was carried out till pigs reached a weight of 115 kg. Feed samples were subjected to laboratory analyses. Body weight (3 times) and feed intake were recorded. Blood samples were collected (2 times) to determine hematological and biochemical indices. Some parameters in meat samples were also determined. The fish meal addition improved (P ≤ 0.05) the average daily gains as well as feed conversion ratio during fattening period and mineral-vitamin premix significantly (P ≤ 0.05) fortified fish meal influence. Fish meal supplement improved (P ≤ 0.05) also some carcass characteristics. Supplementation of the diet with premix additionally decreased (P ≤ 0.05) backfat thickness and increased share of meat in carcass. Fish meal improved (P ≤ 0.05) some meat characteristics and elevated content of some polyunsaturated fatty acids. An increase in hemoglobin, red blood cell, white blood cell and cholesterol level in blood of animals from both experimental groups were also found. The results obtained proved the usefulness of fish meal and mineral-vitamin premix in the fatteners nutrition based on organic diets.