In aquaculture, physiological assessment is required to monitor the health status of fish. Blood is the most responsive system in the organism of hydrobionts to changes in external factors. The study of hematological parameters of fish allows for early diagnosis of diseases, working out the technological mode of breeding and rearing, and selection. The typing of cells in circulating fluids is important for compiling hemocytic and leukocyte formulas characterizing the cellular component of the organism’s immune response. In the present study, convolutional neural network models are developed to classify blood cells of carp and sturgeon fish. The quality of the models is estimated based on the metrics Accuracy and Precision, Recall, F 1 with macro-averaging. Based on the processing of blood images, 1104 images of blood cells of carp and sturgeon fish were prepared, including 15 cell populations: hemohistoblasts, myeloblasts, promyelocytes, myelocytes, metamyelocytes, rod-shaped neutrophils, segmented neutrophils, eosinophils, basophils, monocytes, lymphocytes, erythroblasts, normoblasts, mature erythrocytes, and platelets. Models of a convolutional neural network have been developed to recognize populations of blood cell elements (erythrocytes, leukocytes, platelets) of carp and sturgeon fish. The models were trained on 80% of the prepared images, avoiding the problem of overtraining, as evidenced by the constructed graphs of the loss function (sparse categorical cross entropy) and accuracy during the learning process. The constructed models make it possible to recognize blood cells of carp fish with an accuracy of 75.0% (metric F 1 with macro-averaging is 0.570) and blood cells of sturgeon fish with an accuracy of 76.6% (F 1 with macro-averaging is 0.664).