1. Introduction
Silver perch is an omnivorous, native Australian, freshwater finfish with high Ž
. potential for aquaculture Rowland and Barlow, 1991 . They readily accept pelleted
Ž diets, tolerate crowded conditions and perform well in earthen ponds Rowland et al.,
. 1994, 1995 . Large-scale commercial culture depends on the development of cost-effec-
tive diets. The major constraints in formulating cost-effective diets are a lack of information on nutritional requirements of fish and the digestibility of suitable feed
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ingredients Tacon, 1994; McGoogan and Reigh, 1996 . While a large number of fish species are cultured throughout the world, only the nutritional requirements of rainbow
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trout and channel catfish, have been extensively studied Lall, 1991 . One of the consequences of this lack of information is a heavy reliance on high-quality fish meal as
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a protein base for most intensively farmed aquaculture species Lovell, 1989 . Unfortunately, more than 90 of the fish meal used in animal feeds in Australia is
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imported ABARE, 1998 . However, large quantities of agriculture protein sources are Ž
Ž .. produced locally Allan et al., in press a .
Although there is little information on nutritional requirements of silver perch, data for other species, especially other omnivorous species such as channel catfish and
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tilapia, were used to formulate an experimental diet for silver perch SP35 Allan and
. Ž
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. Rowland, 1992 . This diet has produced fast growth 2 g fish
day and high
Ž
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. Ž
production ; 10 t ha
yr in large-scale farming experiments Rowland, 1995a;
. Rowland et al., 1994, 1995 and forms the basis for several commercially manufactured
diets now available to the industry. Additional nutritional research with silver perch has evaluated a large number of Australian agricultural protein sources for use in formulated
diets. This evaluation has included the determination of digestibility coefficients for dry matter, energy, nitrogen, amino acids and phosphorus for approximately 60 ingredients,
Ž Ž ..
including some processed in different ways Allan et al., in press b . Growth studies to determine maximum inclusion levels for several protein sources considered to have high
Ž potential to replace fish meal have also been completed Allan et al., 1999; in press
Ž . Ž . .
a , b ; Allan et al., unpublished data . Some knowledge of nutritional requirements, information on digestibility coefficients
for a wide range of ingredients, and data on the maximum inclusion levels for key ingredients provides the basis for the use of least-cost programming to formulate diets
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Cho and Kaushik, 1985; NRC, 1993 . In this experiment we evaluated the performance and sensory properties of silver
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perch fed diets with minimal fish meal 5 or 10 , containing Australian agricultural ingredients selected on a least-cost basis using data on ingredient digestibility and
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maximum inclusion levels from previous research Allan et al., 1999; in press a , b ; .
Allan et al., unpublished data . The two ‘‘least-cost’’ or test diets, which differed in fish meal content and nutrient specifications, were compared with a commercially available
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diet SP35 formulated by Allan and Rowland 1992 . To ensure that data obtained from this experiment had direct commercial application, the diets were assessed in a large-scale
pond trial with fish stocked at commercially relevant densities and cultured to a market size of greater than 350 g fish
y1
over a 6-month grow-out period.
2. Materials and methods
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