Cheirogaleus medius inhabits western dry deciduous forests. Fruits, flowers, seeds and the tender parts of plants are dietary staples, with invertebrates being eaten in small amounts and small vertebrates taken on occasion. C. medius, like other dwarf lemur species, accumulates large quantities of fat within weeks in preparation for hibernation. At Kirindy, during the prehibernation fattening period, dwarf lemurs consume mostly fruits with high sugar content, which is then converted to fat deposits, thus the name fat-tailed dwarf lemur (Fietz and Ganzhorn 1999). Individual home ranges approach 1-2 ha. Small family groups consist of the reproductively active female-male pair and their offspring from one or two breeding seasons. During the day, which is the resting period, individuals occupy tree holes with up to five individuals occupying a single shelter (Fietz and Dausmann 2006). The breeding season occurs from September to November, leading to a gestation period of about two months. One to four (usually two) offspring are born in December or January. Full sexual maturity is reached during the second year of life (Mittermeier et al. 2008).

Longevity record in captivity is 29 years at the Duke Lemur Center, NC, USA (Blanco and Zehr 2015).

The updated geographic range of this species is limited to the dry forests of western Madagascar, from Tsingy de Bemaraha to the north to Zombitse to the south. Ranges from sea level to 800 m. 

More generally, this species is likely affected by national trends in forest habitat loss: Madagascar lost 37% of its forest cover from 1973 to 2014, with an annual deforestation rate of 1.1%/year from 2010 to 2014. Almost half of Madagascar's forest (46%) is now located within less than 100 metres from the forest edge (Vieilledent et al. 2018).

This species is listed on Appendix I of CITES.

Its presence is reported at Tsingy de Bemaraha National Park, CNFEREF Kirindy, Kirindy Mitea National Park, Analalava and Zombitse. There are ~25 individuals of Cheirogaleus medius housed at the Duke Lemur Center, North Carolina, USA as of 2019.