To ensure the introduction of digital technologies in ichthyology and aquaculture, it is necessary to develop the basis for the preparation of relevant information. It is proposed to use the features of the fish's body shape to provide material for the programming process. The purpose of the work is a preliminary study of methodological approaches to searching and applying information to substantiate a digital model of a specific species of fish - roach Rutilus rutilus L. 1758. Collection and processing of material were carried out using traditional methods of ichthyological research. The sum of the ratios of the length from the top of the snout to the vertical from the base of the pelvic fin to the beginning of the dorsal fin, the width, height and girth of the body of the roach to the length of its body from the top of the snout to the end of the scales is determined. It can be accepted as the basis for digitalization of the species - a “morphological passport” of the roach, taking into account the five measurements and four relationships. This determined the normal development of roach in the Dnieper-Bug Canal in the Pinsk district of the Brest region, Republic of Belarus. To justify the use of an impersonal form of data presentation corresponding to all types of fish, we recorded for a separate species, using the example of roach, a certain desired “unit” - the length of the body from the top of the snout to the end of the scale cover. A unique combination of four values of the studied relationships, along five dimensions, was obtained, which can be taken as the basis for identifying roach as a separate biological species, which began with a value of 1.401 in fingerlings, tomaximum value of 1.665, was recorded, in four-year-olds.