Malaysian fire snails (Platymma tweediei), face threats to their environment, including habitat destruction and the illegal wildlife trade. Captive breeding projects are likely to play a role in the survival of this species; however, mortality in captive populations potentially presents a significant challenge. This paper presents the results of histopathologic examination of tissues from 10 P. tweediei casualties in a captive population at Chester Zoo. In October 2022, a captive breeding program was established with 20 wild-born P. tweediei. All adult founder animals died by July 2023, of which 10 were submitted for necropsy and histopathology of organs. Significant histologic abnormalities were present in all cases, primarily affecting the lung, integument, and heart. Histological analyses indicated a pneumonia-like condition was prevalent in all cases, suggesting potential environmental factors contributed to respiratory infections. A variety of possible etiologic or secondary infectious agents were present in sections including bacteria, fungi, and trematodes. There were some challenges in interpreting the histologic changes, emphasizing the need for more reference material and studies on the normal histologic anatomy of terrestrial gastropods. The findings underline the importance of understanding mortality events in captive populations to improve husbandry and environmental management. Additionally, the study recommends the submission of fresh specimens for necropsy to enhance diagnostic capabilities, such as bacterial culture, and suggests targeted sampling strategies for future research on captive snail species.