A 2-day-old neonate was admitted to hospital with septicaemia and meningitis found to be caused by Plesiomonas shigelloides. In spite of a course of intravenous ampicillin and cefotaxime he died 2 days later. We could not isolate the bacterium from the faeces of the mother and her dog, nor from the aquarium-water of her parents-in-law nor from the aquarium-water and fish of the doctor who delivered the baby. We briefly review the literature on P. shigelloides meningitis and its epidemiology.