Although the common snapping turtle Chelydra serpentina is cultured commercially in the United States, little information is available on nutritional and culture requirements. This study was conducted to evaluate the effects of dietary energy: protein ratio and stocking density on survival, growth, feed consumption, feed conversion, liposomatic index, dress-out percentage, and productive protein value of cultured, common snapping turtles. Hatchling turtles were stocked at 29 and 58 animals/m2 and fed one of seven prepared diets. Six diets contained 30, 35, or 40% protein at two digestible energy (DE) levels (7 or 9 kcal DE/g protein); the seventh was a reference diet (66% protein and 5 kcal DE/g protein) formulated to equal or exceed the whole-body essential amino acid composition of wild, common snapping turtles. Turtles stocked at 58/m2 exhibited greater mortality, lower weight gain, higher feed consumption, less-efficient feed conversion, lower liposomatic index, and lower productive protein value than turtles stocked at 29/m2 (P < 0.05). The reference diet produced the greatest weight gain (P < 0.001). The superior performance of turtles fed the reference diet suggests that: 1) the protein (amino acid) content and/or energy: protein ratio of the reference diet was superior to that of the other diets tested; 2) improvements in growth parameters can be made with dietary manipulation; and 3) high levels of plant protein can be used in prepared, snapping turtle diets.