SUMMARYThe aim of this study was to e valuate the performance of dimethylacetamide (DMA) as cryoprotectant at three concentrations: 8% (0.85 M), 10% (1.07 M) and 12% (1.29 M), combined with glucose at 6% (0.33 M) and egg yolk at 12%, to cryopreserve semen of bocachico Prochilodus magdalenae. The semen was diluted at 1:4 ratio in the cryoprotective solution, packed in 2.5 mL straws and frozen in liquid nitrogen vapor (LN 2 ) for 30 minutes, then it was stored in a container with LN 2 of 34 L. The concentration, total motility, progressive motility and sperm speed in both fresh (control) and cryopreserved-thawed semen were evaluated using Sperm Class Analyzer (SCA). Straws were thawed in serological bath at 60°C for 45 seconds. Fertility and hatching were evaluated inseminating 2 g of eggs (1,540 eggs/g) at a rate of 320,000 spz/egg. Fresh semen recorded the highest values of total motility, total progressive, curvilinear speed and linear speed with regard to cryopreserved-thawed semen (P < 0.05); whereas cryopreservedthawed semen with DMA 8% and 10% recorded the higher values for these variables, without significant differences between them (P > 0.05). DMA 12% reported the lowest values of all the variables evaluating semen quality. Fresh semen obtained values of 74.0 ± 5.3% and 62.3 ± 3.1% for fertility and hatching, respectively, while cryopreserved-thawed semen with DMA at 8% produced adequate fertility (60.4 ± 8.4%) and hatching (50.1 ± 9.8%) values. The results of this study suggest that the cryoprotectant solution composed of DMA at 8%, glucose at 6% and egg yolk at 12% is a viable alternative for the cryopreservation of semen of bocachico.Key words: dimethylacetamide, cryopreservation, milt, Prochilodus magdalenae. RESUMENSe evaluó dimetilacetamida (DMA) como crioprotector, a tres concentraciones: 8% (0,85 M), 10% (1,07 M) y 12% (1,29 M) combinado con glucosa 6% (0.33 M) y yema de huevo 12% para crioconservar semen de bocachico Prochilodus magdalenae. El semen fue diluido en proporción 1:4 en la solución crioprotectora, empacado en pajuelas de 2,5 mL y congelado en vapores de nitrógeno líquido (N 2 L) durante 30 minutos y luego almacenados en un termo de N 2 L de 34 L. La concentración, movilidad total, progresividad y velocidad tanto en semen fresco (control) como en semen crioconservadodescongelado se evaluó con ayuda de Sperm Class Analyzer (SCA). Las pajuelas fueron descongeladas en baño serológico a 60°C durante 45 segundos. La fertilidad y eclosión fueron evaluadas inseminando dos gramos de huevos (1540 huevos/g) a razón de 320.000 spz/ovocito. El semen fresco registró mayores valores de movilidad total, progresividad total, velocidad curvilínea y velocidad lineal con respecto al semen crioconservado-descongelado (P < 0,05); mientras que el semen crioconservado-descongelado con DMA 8% y 10% registraron los mayores valores en estas mismas variables, sin observarse diferencia significativa entre ellos (P > 0,05). DMA 12% reportó los menores valores de todas las variables que evaluaron la calidad semina...