Growth and Survival of Juvenile Queen Conch Strombus gigas Fed Artificial Diets Containing Varying Levels of Digestible Protein and Energy

Aquaculture methods for queen conch Strombus gigas have been established for several decades. However, there is a need to improve husbandry techniques for the grow out of juveniles. The purpose of this study was to determine the growth and survival of juvenile queen conchs fed artificial diets with increasing levels of a red alga Agardhiella sp. Agardhiella, soy protein isolate, and fish oil were increased at the expense of catfish feed, wheat flour, or both to keep the diets isonitrogenous (38% crude protein [CP]) with increasing protein to energy ratios (83-96 mg CP/kcal). Yttrium was also incorporated as an inert marker for determining the digestibility of dietary nutrients. Juvenile queen conchs were stocked at 75/m2 for a total of 16 conchs per replicate (three replicates) and were fed 125 mg of diet per conch each day for 6 months. Dietary crude protein ranged from 31% to 38%. The dietary lipid, moisture, energy, ash, fiber, carbohydrate, and yttrium in each diet were also determined. Juvenile conchs were measured (shell length and wet weight) every 6 weeks. At the end of the experiment, feces were collected to determine protein, energy, and dry matter digestibility. Results indicated the highest growth rates (0.10 mm/d and 0.11 mm/d) and survival were for conchs that were fed diets containing a soy protein isolate protein substitution of 15% or less. This study highlights the importance of the protein source in the artificial diets of juvenile queen conchs.