Pygmy Marmoset

It gnaws holes in bark to release gum and draws about 70% of its calories from exudates, supplemented by insects, fruit and nectar. It lives in stable troops of 2-9 in which one dominant pair breeds, typically producing twins about twice a year. It is diurnal, and lives 15-20 years in captivity. A 2018 molecular study split the eastern populations off as Cebuella niveiventris, so identifying traded animals to species is not straightforward. Both species are Vulnerable. It was placed on CITES Appendix I in 1977 and has been on Appendix II under the order-wide primate listing since 1979. Japan does not permit primate imports for pet purposes under the Infectious Diseases Control Act, so only domestically bred animals circulate, and sellers need animal-handling business registration. As a troop-living animal it should not be kept alone, and it needs a tall enclosure and a diet that reproduces gum and insects. It is very rarely available in Japan.

Source: Wikipedia (CC BY-SA 4.0)

The Pygmy Marmoset lives 15-20 years.

The Pygmy Marmoset grows to Head-body 12-16cm / 85-140g.

The pygmy marmoset (Cebuella pygmaea) of the western Amazon Basin in Ecuador, Colombia, Brazil, Peru and northern Bolivia is the smallest monkey, with a head-body length of 12-16 cm, tail 17-23 cm and weight 85-140 g.