Despite their small size, marmosets need a relative large area. Your cage should be at least 6 ft tall, 3 ft deep, and 6 ft wide. The width of the cage is important since marmosets like to jump around. Just like it is with all monkeys, the bigger the cage, the better. Very often people believe that because marmosets are small, they only require a small cage but nothing is less from the truth.
If possible, create outdoor enclosures with a heated indoor enclosure attached to it. Marmosets need vitamin D3 which can only be found in sunlight and this for their bone structure. Remember, vitamin D3 is only produced through natural sunlight and is none existent through glass. If you’re unable to provide an outdoor enclosure for your marmosets, make sure you sprinkle vitamin D3 powder over their food a few times a week.
Like all monkeys, marmosets will spend hours exploring their home. It is therefore important to change their environment every week to prevent boredom.
For Outdoor enclosures use: Branches, Grass floors, Trees, Swings, Platforms, Rocks
For Indoor enclosures use: Branches, Peat/Sawdust/Wood chip floors, Branches, Swings, Wooden nestbox, Bird Toys
Again, as mentioned above, I cannot stress the importance of changing their environment from time to time enough.
You must clean indoor cages every week. Marmosets scentmark their cage constantly, therefore it is very important that you don’t sterialize their cage at once. Clean the nestbox and the cage at different times. Use a mild desinfectant to clean their cage.
They need a temperature of 70F-80F in indoor cages. It is also recommended to use heat lamps so they have places where they can sunbath. Make sure your marmosets are unable to reach the heat lamp to prevent them from getting burned. For outdoor cages, don’t forget to provide some shade in the summertime.
A humidity of 40 to 60% is perfect. You can use moist peat (floor) to maintain a high humidity.