Just saw this article:
Volkman, E.T. et al. 2004. Hatchery performance attributes of juvenile lake
sturgeon fed two natural food types. N. Am. J. Aquaculture 66: 105-112.
Paper describes a study in which fish growth (starting size of 93-98 mm FL)
was evaluated for a continuum of diets ranging from 0% bloodworms & 100%
brine shrimp to 100% bloodworms & 0% brine shrimp. Values of all growth
attributes (final size and weight, rate of growth, percentage weight gain,
food conversion effiicency, whole body protein, lipid, and gross energy) were
directly correlated with the amount of bloodworms in the diet and were
highest for the 100% bloodworm diet. Differences were observable after just
four weeks, and were pronounced-in-10 weeks.
This isn't to say that bloodworms (chironomids) are better than brine shrimp
for raising all (or any) fish - just some (or this one) species.
According to the "Guaranteed analysis" of the foods I use:
bloodworms consist of 4.5% protein [min], 0.2 % fat [min], 0.7 % [max],
95.0% moisture [max]
brine shrimp of 5.8% protein [min], 0.6 % fat [min], 0.25 % [max], 92 %
moisture [max]
Bloodworms are a little more "watery" but appear to have a high protein to
fat ratio (>20X) and high fiber (almost up to 1%).
Brine shrimp seem to have a lower protein to fat ratio (< 10X) and lower
fiber (up to 1/4 %).
Some fish may do better on a high-fat and low fiber diet, but apparently lake
sturgeon here did not.
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