Three weeks ago, a baby marmoset, the size of a man's thumb, was born to the zoo's marmoset couple.
The parents, timid at the best of times, are particularly protective of the tiny offspring, only presented to the cameras on Monday, and so the zoo has not been able to determine the sex of the baby marmoset.
Once they have the sex the zoo can look at naming the mini monkey, favorite names so far being Thumb or Fly.
Known as the smallest New World primate, a marmoset's body is on average 13cm long. They are native to Bolivia, Brazil, Colombia, Ecuador, and Peru and usually live in groups of 2 to 6 marmosets. On average they weigh fewer than 100 grams, according to Skopje Zoo.