Allen's swamp monkey is an unusual guenon that inhabits moist forests and swamp forests of Central Africa and is accustomed to water, not shying away from swimming. It primarily eats fruit and invertebrates, and also consumes fish, nectar, flowers, and seeds. Its body is sturdy with short limbs, and a webbed structure may be present between the fingers. Groups are multi-male multi-female of up to about 40 individuals and may split while foraging; reproduction is nonseasonal and females give birth to one or two young. Its conservation status is Least Concern.