Floating masses of vegetation are commonly seen in the southern region of Lake Malawi.
These floating islands disperse littoral fishes across deep portions of the lake.
Six islands were sampled and all yielded fishes. The 129 individuals collected belong
to ten species, including one mormyrid, one cyprinid, two clariids, one cyprinodontid,
four cichlids and one mastacembelid. Most of the species are characteristic of lakeshore
swamps and are not endemic to Lake Malawi. Dispersal by floating islands may increase
gene flow between disjunct populations of widespread species, particularly those inhabiting
swamps. Such dispersal, theoretically, could also serve to establish founder populations
of geographically isolated species.