Shrimp is bad if its natural color is slightly off and it emits a strong fishy odor; fresh shrimp meat is white in color and gives off a fresh, light aroma. Additional signs of spoiled shrimp include a slimy texture and an ammonia, iodine or chlorine scent. If the shells are dangling off the sides of the shrimp, this indicates deep spoilage. Raw white shrimp that appears to be turning dark pink typically indicates meat deterioration.
In order to avoid food-borne illness from fresh shrimp, it must be immediately refrigerated and eaten or discarded within two to three days. Shrimp is extremely perishable and is a common culprit in food-borne illnesses, especially on cruise ships and at hotels that offer lavish buffets. Shrimp that sits out for extended periods of time and does not meet the temperature standards can quickly go bad. Spoiled shrimp quickly develops bacteria, and the bacteria are what lead to food poisoning. E coli and salmonella are the main bacterial strains found on tainted shrimp.
Ingesting bad shrimp can cause stomach discomfort, vomiting and diarrhea, and dehydration is possible if symptoms last longer than 24 hours. Numbness or tingling may occur, beginning in the mouth and spreading to the arms and legs, possibly causing temporary paralysis.