J. Appl. Ichthyol. 11 (1995), 205-214 zyxwvu 0 1995 Blackwell Wissenschafts-Verlag, Berlin ISSN 0175-8659 zyxwvutsrq Received: September zy 5, 1994 Accepted: March 8, 1995 zy Application of nutrient requirement data under practical conditions: special problems of intensive and semi-intensive fish farming systems By A.G.J. TACON Inland Water Resources and Aquaculture Service, Fishery Resources and Environment Division, Fisheries Department, Food and Agriculture Organization of the United Nations (FAO), zyx 00100 Rome, Italy Summary Methodological approaches for undertaking research on the dietary nutrient requirements of farmed fish should ensure that the studies are designed and conducted in such a manner that the ensuing results can be applied under practical farming conditions. Sadly, the majority of studies to date, and in particular those for omnivorous warm water fish species, have had little or no practical a licability; the bulk of nutrient requirement studies having been conducted under controlled artificiaf faboratory conditions. Despite the fact that silver car (Hypophthalmichthys molitrix), common carp (Cyprinus ca io), grass carp (Ctenopharyngodon ideli), bi head carp ( H y ophthalmichthys nobilis) and milkfish (CTanos chanos) are the top five most cultivated f s h species in tie world (total a uaculture production of these fish s ecies in 1990 totalled 4.8 million metric tonnes or 57% of the tot1 world farmed finfish production), ktle or no information exists concerning their dietary nutrient requirements under practical semi-intensive pond farmin conditions. To a large extent this has been due to the reluctance of the conventional laboratory-basecf fish nutritionist to work under applied field conditions and the difficulty of uantifying the contribution of natural food organisms in the overall nutritional budget of pond raise%fish. If meanin ful conclusions are to be drawn from nutrient requirement studies it is essential that the experimentaf fish be reared under conditions mimicking as far as possible those of the intended farm production unit and environment, including holding facility (indoor or outdoor tank, cage or pond), elleting, drying; diet texture, form, shape, size, buoyancy and water stability), feeding metaod (ha;{ demand or automatic feeding; feeding frequency and feeding rate zyxwvutsrq - fixed or satiation feeding), water quality (temperature, turbidity, salinity, oxygen and mineral concentration; water exchange rate, water circulation pattern and artificial aeration), photoperiod (artificial or natural) and fish stocking density. Finally, but not least, it is essential that the growth performance of the experimental fish be at least equal to or greater than that of the target fish species under practical farming conditions so that dietary nutrient requirements can be ascertained under conditions of maximum attainable growth. eed preparation technique ( rinding Introduction Since the report of the EIFAC, IUNS and ICES Working Group on Standardization of Methodology in Fish Nutrition Research (CASTELL and TIEWS 1980) a variety of review papers have been published dealing with methodological approaches to fish nutrition research and development; UOBLING 1983; CHO et al. 1985; TACON and COWEY 1985; TALBOT 1985; DE SILVA 1988, 1989, 1991; KAUSHIK 1989; LOVELL 1989; MARTINEZ et al. 1989; WEE 1989; AKIYAMA 1991; D’ABRAMO and LOVELL 1991; TACON 1991a; WORLD BANK et al. 1991; CHO 1992; COWEY 1992; DE SILVA and DAVY 1992; PFEFFER 1992). In the main, these reviews have dealt more with the standardization in approach, design, analysis and reporting of nutrition research for the benefit of fellow researchers and col- laborative laboratories than with the applicability of the data generated from such studies to practical farming conditions. U. S. Copyright Clearance Center Code Statement: 0175-8659/95/1104-0205 $1 1.00/0