Introduction

Using feeds in aquaculture (sometimes referred to as aquafeeds) generally increases productivity. However, to maximize cost-effectiveness, it is particularly useful in small-scale aquaculture to utilize locally available materials, either as ingredients (raw materials) in compound aquafeeds or as sole feedstuffs.

There is also a vital need to seek effective ingredients that can either partially or totally replace marine ingredients as protein sources in animal feedstuffs generally, in particular in aquafeeds. While this broad topic is not dealt with in this review, many introductions to the literature of the past two decades are available, including New and Csavas (1995), Tacon (1994; 2004;), Tacon, Hasan and Subasinghe (2006), Tacon and Metain (2008), New and Wijkstrom (2002), FAO (2008) and Huntington and Hasan (2009).

This review deals with the characteristics of aquatic raw materials for use as feeds in small-scale aquaculture, namely algae (principally macro-algae – commonly referred to as seaweeds) and aquatic macrophytes. Aquatic macrophytes are aquatic plants that are large enough to be seen by the naked eye. They grow in or near water and are floating, submerged, or emergent.
Information includes current and potential usage of these materials by small-scale aquafarmers for target fish and crustaceans, together with details on their classification, characteristics (including such factors as their natural distribution and environmental requirements), production and chemical composition.
The review has been divided into seven major sections: one dealing with algae; four sections on floating macrophytes (namely Azolla, duckweeds, water hyacinths and others); a section on submerged macrophytes; and one on emergent macrophytes. Finally, the review contains a concluding section which summarizes previous chapters.