Habitat types vary from rocky shorelines to sandy beaches and from wooded hillsides to swamps and lagoons. A range of underwater habitats arerepresented including the sandy zone, the weedy zone, the rock-sand interface, the intermediate zone and the reed beds.
The islands, especially Mumbo and Boadzulu, are important nesting areas for several thousand white-breasted cormorant Phalacrocorax lucidus. Reptiles include crocodile Crocodylus niloticus and abundant water monitor lizards Varanus niloticus on Boadzulu Island. Five shoreline villages, Chembe, Masaka, Mvunguti, Zambo and Chidzale, are included within enclaves in the park.
The park has been zoned so that traditional fishing methods aimed at catching migratory fish are permitted in limited areas, although in most of the park the resident fish are completely protected. Some 16,000 people make a living from the Lake and 40,000 tonnes of fish are taken annually for local consumption.
Lake Malawi contains the largest number of fish species of any lake in the world, probably over 500 from ten families with perhaps half occurring in the park area. Endemism is high (thought to exceed 90%) and adaptive radiation and speciation within the lake is remarkable. Particularly noteworthy are the Cichlidae, of which all but five of over 400 species are endemic to Lake Malawi. Of particular interest is the 'mbuna' rock fish. More than 70% of mbuna are not described and the taxonomic affinities of many are uncertain. Other fish species include 28 endemic to the lake.
The Department of Fisheries has a research station at MonkeyBay. Research has concentrated on fish, conducted mainly by overseas and national scientists and graduates (Department of National Parks and Wildlife, pers. comm., 1995). Although there are no human settlements within the boundaries much of the lakeshore is heavily populated. Villages on the peninsula (population of about 5,400 in 1977) are cut off between the park and the lake and local people are dependent on fishing for a livelihood as the soil is poor and crop failure frequency is about 50%.
The brightly-coloured mbuna provide a substantial export trade to collectors. Clearing of timber for building, firewood and cultivation has increased (particularly on Nankoma Island, part of Mumbo Island, around Chembe village and the Mwenya and Nkhudzi Hills). Unsightly and unplanned visitor shacks at Cape Maclear will be removed when a new lodge is built.