Diet, growth and recruitment of wild zebrafish in Bangladesh R. S PENCE*†, M. K. FATEMA‡, S. ELLIS*, Z. F. AHMED‡ AND C. SMITH* *Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, U.K. and ‡Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh (Received 6 July 2006, Accepted 17 February 2007) The diet of zebrafish Danio rerio in Bangladesh consisted primarily of zooplankton and insects. Zebrafish was an annual species, with the main period of reproduction commencing just before the onset of the monsoon season. Growth rates varied with age and season, with the period of most rapid growth in early life during the monsoon months. # 2007 The Authors Journal compilation # 2007 The Fisheries Society of the British Isles Key words: Cyprinidae; ecology; food; length-frequency analysis; model species. The zebrafish Danio rerio (Hamilton, 1822) is a small (c. 30 mm standard length, L S ) cyprinid first described in the Ganges River delta. It is a popular aquarium species and is a model organism of enormous significance in develop- mental genetics (Kimmel, 1989; Granato & N ¨usslein-Volhard, 1996; Grunwald & Eisen, 2002). Little is known, however, about the natural biology or behaviour of the zebrafish, and few studies have been conducted on wild populations. The natural range of the zebrafish is centred around the Ganges and Brahmaputra River basins in north-eastern India, Bangladesh, Nepal and Northern Myan- mar (Laale, 1977; Barman, 1991). This region has a monsoon climate, with wide seasonal variation in the extent of freshwater habitats. The zebrafish is primarily a flood-plain rather than a riverine species, inhabiting shallow, slow moving or standing water bodies, particularly around rice-fields (McClure et al., 2006; Spence et al., 2006). The purpose of this study was to describe temporal changes in the diet of wild zebrafish using gut content analysis, and identify recruitment patterns and estimate growth parameters using length-frequency analysis. †Author to whom correspondence should be addressed. Tel.: þ44 (0) 116 252 3342; fax: þ44 (0) 116 252 3330; email: rs153@le.ac.uk Journal of Fish Biology (2007) 71, 304–309 doi:10.1111/j.1095-8649.2007.01492.x, available online at http://www.blackwell-synergy.com 304 # 2007 The Authors Journal compilation # 2007 The Fisheries Society of the British Isles