I knew next to nothing about fish farming until last summer when I helped to copyedit the English version of Yves Fermon's "Subsistence fish farming in Africa: a technical manual." I am still no expert, but at least now when I hear that there's a monk in a fish pond I know better than to ask if he can swim.
Yves Fermon's new e-book, available in English and French and published by the NGO Action Against Hunger (in French Action Contre le Faim, or ACF), differs from most other publications on fish farming in Africa in two important respects.
First, as its title implies, it describes a tested, practical method for constructing and maintaining fish ponds that could supply a few families or a small village, or as Fermon says "a semi-intensive, artisanal fish farming operation for self-consumption that employs polyculture and requires a limited degree of external inputs and maintenance." It is not a how-to for starting a commercial fish farming enterprise, even a small one. In addition to step-by-step instruction for all phases of fish pond design, construction and maintenance, there is useful biological and distributional information provided for all of the species commonly used in fish farming: tilapias and others such as clariid catfishes and the osteoglossid Heterotis niloticus.
Second, this book promotes environmentally responsible fish farming. While the threat tilapias pose to native fish species in Asia, the Americas and on island ecosystems where they have been introduced is relatively well known (they've made the IUCN's Most Invasive 100 list), it is less appreciated that introduced tilapia are a problem in Africa itself. Although this group of cichlid fishes comprises more than one hundred species, farming operations have preferred to use the same few species over and over again, importing stocks from distant drainage basins even if local tilapias are available and would likely perform well. Because we lack good data on population sizes in most parts of Africa, it's hard to know how much impact such introductions have caused to native species, but non-native tiliapias are commonly encountered even far from human habitation (e.g. see the 'Fishes of the Lukuga' article below).
This is the first aquaculture book I've seen that instructs the reader to identify the drainage basin and ichthyofaunal region in which the fish ponds are to be located (maps are provided) and then includes a table of species native to each region that should be used in place of exotic species. Bravo! For being biodiversity-friendly, it seems completely appropriate to plug this book on a site dedicated to African fish diversity.
In fact, as of right now, this website is the only place you can get this pdf e-book (by permission of ACF and Yves Fermon) and the price is right: it's a free download.