Introduction. The study of anthroponyms in general and surnames in particular is one of the urgent problems of modern Ukrainian onomastic science, which has important theoretical and practical significance not only for linguistics but also for history, geography, and ethnology. Despite the close attention of Ukrainian scientists to the study of various aspects of anthroponymy at the end of the XXth — the beginning of the XXIst centuries, it should be said that the study of anthroponyms of individual microsystems, such as settlements, social groups, and, especially, surnames derived from personal names, is only at the initial stage. The purpose. The purpose of the article is to investigate the place of the surnames of the surname microsystem “Karas (karas)” in the system of Ukrainian surnames, to describe the methods of their creation, to distinguish the affixes with the help of which the surnames of this microsystem were formed, to analyze their prevalence on the territory of Ukraine. Materials and methods. The dataset of the investigation was the materials of the website “Ridny” (Ridny), which records 876,000 surnames of residents of Ukraine, of which only 77 surnames belong to the “Karas” surname microsystem. The descriptive method and its main means are used in the article: inventory and systematization of language material in synchrony. Results. The result of the conducted research is the establishment of the place of the surname microsystem “Karas(karas)” in the system of Ukrainian surnames, the description of the methods of creating surnames of this microsystem, the identification of affixes with the help of which these surnames were formed, the determination of the limits of the prevalence of surnames of the surname microsystem “Karas(karas)” in the territories of Ukraine. Conclusions. The analysis of the surnames of the surname microsystem “Karas(karas)” gave reasons to conclude that although this microsystem is relatively small, it is rather diverse in terms of methods and means of creation. The most common surname of this microsystem is the surname Karas (3,550 bearers), which occupies the 1,125th place in the general list of residents of Ukraine, and the most derived surnames are formed from the surname Karas (18 surnames). The most common way of creating surnames of the surname microsystem “Karas (karas)” is the suffix (45 surnames). Most often, the suffixes -ov (7 cases), -enk (-enk) (5 cases), -sk-, -ich(-ich) (4 cases each) were used to create such surnames. 19 surnames are formed by the inflectional method. Among the residents of Ukraine, there are 11 bearers of double surnames. Of the 77 surnames of the surname microsystem “Karas (karas)” that are common in Ukraine, 35 or 45.45 percent are russified, that is, appeared in the Ukrainian language under the influence of the Russian language. In the future, the problem of the origin, peculiarities of creation and distribution on the territory of Ukraine of surnames derived from other names of river and sea fish, including a comparative aspect, and some other problems will need to be studied.