Karimi's fat-tailed mouse opossum has a thick tail whose size changes with seasonal food availability. Juveniles were captured in both wet and dry seasons, suggesting it might breed year-round.
Its fat tail changes in size by season in relation to food availability. The coat is usually darker above, paler on the sides, and white below, although some individuals do not show the pattern clearly.
Juveniles were captured in both wet and dry seasons in Brazil. This suggests that the species might breed throughout the year, but little else is known about its reproduction.
An extinction-risk assessment has not been added yet.