Zoos are under increasing pressure to strategically manage their collections to maximize visitor attendance, financial income, and their contribution to conservation. As a result, the compositions of zoo collections are undergoing significant changes. Many zoos are keeping fewer species and prioritizing keeping large flagship animals that are more attractive to the public. To understand the effects these changes are having on captive reptile numbers, we have analyzed the trends in reptile holdings between 2003 and 2023 at UK zoos. Our findings show that despite an overall increase in reptile numbers in the period analyzed, there has been a dramatic decline in the number of venomous snakes held at UK zoos, and as a result, venomous snakes are being excluded from many of the conservation benefits that zoos provide. To understand the key factors contributing to the decline in venomous snake numbers, 57 staff members across 35 different BIAZA–accredited zoos were surveyed. Results from the survey identified that a perceived increased risk of harm, increasingly stringent health and safety regulations, and increased husbandry requirements were all key contributing factors to why venomous snake numbers at zoos are in decline.