Brine shrimp Artemia spp. nauplii are a popular first-feed used in ornamental aquaculture due to their convenience, excellent digestibility, and appropriate nutritional profile for larval fish, while also provoking an active feeding response with their rapid movements. Major drawbacks are the variability in cost and nutritional profile. Alternatives include inert formulations, such as commercially available microparticulate and liquid microdiets; however, these diets lack intrinsic movement, and thus, larval ingestion rates may not be enough to support the rapid growth and development necessary during this early life stage.
Three amino acid feed attractants (L-alanine, betaine, and L-tryptophan) top-dressed onto commercially available microparticulate diets and two brands of liquid Artemia replacement diets (Liqualife® and EZ-Artemia®) were tested in separate investigations to determine if such alternatives could be cost-effective options. Experimental systems consisted of 3L tanks with flow-through filtered water each containing 75 Albino Rainbow Sharkminnow Epalzeorhynchos frenatum larvae fed twice daily for 7 to 21-days depending on the experiment. Feed attractants were evaluated in a series of inclusion rate experiments to identify which attractants, and in what amounts, increased survival and growth. For the liquid Artemia replacement diets, Artemia nauplii were replaced at 50% and 100% with the goal of identifying which brand performed better and if the live Artemia nauplii diet could be entirely replaced by a more cost-effective and convenient alternative. Survival and standard length were used to gauge diet success.
Feed attractant enhanced diets showed increases in survival by as much as 10% (Figure 1); however, neither brand of liquid Artemia replacement diet showed any increase in survial or growth when compared to the live Artemia nauplii reference diet.