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New Crops News, Spring 1993, vol. 3 no. 1

Soft-shell Crayfish Production in Indiana

The environmental conditions necessary to successfully produce soft-shell crayfish in Indiana have been determined by Paul B. Brown, Department of Forestry and Natural Resources, and member of the New Crops Center. Water temperatures of 20°C and a minimum of 8 hours light per day increased molting activity of a native species of crayfish (Orconectes virilis, the northern or fantail crayfish) compared to warmer temperatures or longer light periods.

However, diets for this species were not considered optimal. Studies over the past two years at Purdue were designed to improve dietary formulations for this important aquaculture animal. The dietary essentiality of vitamin C was determined. This is the first report of vitamin C needs in a freshwater crustacean. Additionally, various forms of vitamin A were found to influence coloration of the exoskeleton. Crayfish fed the available crustacean diets typically develop a blue pigmentation that may not be desirable in the marketplace. The hypothesis that vitamin A affected exoskeleton color was formulated and tested with native Indiana species. Crayfish fed any form of vitamin A (retinol, retinal, retinoic acid, or retinyl-palmitate) were atypically pigmented, while those fed a vitamin A precursor, ß-carotene, developed normal pigmentation. This result is the first indication that crustaceans pigmentation is influenced by diet.

Taken together, these studies represent advances in our understanding of nutritional needs of crayfish and should facilitate development of soft-shell crayfish production for Indiana producers.