Mwanza and Lake Victoria have a sparse but interesting literature, mostly bound up with the colonial history of the lake and the environmental disaster of the Nile perch introduction.
Hippolyte Werly, Darwin's Nightmare (2004) — technically a film rather than a book, but the script and the journalistic record around it are essential context for Mwanza today. The documentary follows the chain that turns Lake Victoria's Nile perch into fillets in European supermarkets, and the human toll along the way: prostitution at the docks, displaced fishing communities, planes that bring fish out and weapons back in. Watch it before you visit Mwaloni Fish Market.
Henry Morton Stanley, Through the Dark Continent (1878) — Stanley's account of his expedition to circumnavigate Lake Victoria in 1875, in which he passed Mwanza and named Bismarck Rock. The Victorian prose is heavy going but the descriptions of the lake and its peoples are vivid.
M.G. Vassanji, The Book of Secrets (1994) — set partly in colonial Tanganyika, this novel by the Tanzanian-Canadian writer captures the experience of the Indian community on the lake, which has been part of Mwanza's commercial life for over a century.
Peter Matthiessen, Sand Rivers (1981) — not about Mwanza specifically but the best book on the Tanzanian bush, written by one of the great American naturalist-writers about a foot safari in the Selous. The right book to read on a long bus from Mwanza to anywhere else.