SUMMARY—Collections of freshwater crayfish were obtained from 22 sources representing the major commercial crayfishing areas in Louisiana, and analyzed for coliforms, Escherichia coli, fecal streptococci, coagulase‐positive staphylococci, Salmonella and Clostridium botulinum type E. Growth patterns for E. coli, Staphylococcus aureus, Streptococcus faecalis and Salmonella typhimurium in raw and cooked crayfish flesh, and in a crayfish‐containing commercial‐type substrate were determined at 5, 25, and 37°C. C. botulinum type E toxin production was determined at intervals of storage in ice pack and at 5 and 30°C.Coliforms, E. coli, fecal streptococci, coagulase‐positive staphylococci, Salmonella, and C. botulinum type E were found in 100, 92.6, 94.1, 3.0, and 0, respectively, of the samples analyzed. Staphylococcus aureus and Salmonella typhimurium grew well in all three of the substrates at 25 and 37°C. Streptococcus faecalis and possibly E. coli showed suppressed growth in the raw flesh, but both grew well in cooked flesh and the commercial‐type substrate. None of these four organisms grew at 5°C. C. botulinum type E produced toxin in all three of the substrates within 48 to 72 hours at 30°C and after 33 days at 5°C.Toxin was not produced at 56 days in ice‐pack. The pH increased in the raw and cooked flesh, with extended storage time, to above 8.0 and the toxin became inactive. In the commercial‐type substrate, the pH decreased to 5.7 and the toxin remained active. When the pH of the commercial‐type substrate was adjusted to 8.5 with NaOH, th
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