Dietary Protein Source and Level Affects Growth in Neon Tetras

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AbstractNutritional studies for aquarium fishes like the neon tetra Paracheirodon innesi are sparse in comparison with those for food fish. To determine the optimum dietary protein level and source for growth of neon tetras, diets were formulated to contain 25, 35, 45, and 55% dietary protein from either marine animal protein or plant protein sources in a 4 × 2 factorial treatment design. Neon tetras (initial weight, approximately 0.12 g) were reared in 5‐L fiberglass tanks (25 fish/tank, 3 tanks/diet) in a freshwater recirculating system. Fish were hand‐fed the experimental diets three times per day for 12 weeks. Average weight gain of neon tetras fed diets with marine protein sources was significantly higher than that for fish fed diets based on plant proteins. Fish fed diets containing 45% or 55% crude protein had significantly greater weight gain than did fish fed 25% crude protein from either protein source. Fish fed 25% crude protein from either source had a significantly higher feed conversion ratio than did those fed 45% or 55% crude protein. Survival ranged from 71% to 84% and was not significantly altered by dietary protein source or level. No significant interactions between dietary protein source and level were found for any of the response variables. As the price of fish meal continues to increase, the formulations of feeds for food fish will probably contain lower amounts of fish meal and higher amounts of plant protein products. If a similar trend occurs for ornamental fish diets, further refinement of nutritional requirements and assessment of palatability of feed ingredients for neon tetras and other aquarium species will be required.