A series of mark-recapture studies were conducted between 2017 and 2018 for purposes of assessing multiple hypotheses regarding post-release survival of the Kihansi Spray Toad in the Upper Spray Wetland. In a pilot study conducted in May 2017, 200 of the 590 released animals in Enclosure 2 in the Upper Spray Wetland were individually marked. Animals that were treated for intestinal parasites had higher weekly apparent survival than animals that were not treated although differences were not significant based on an overlap of the 95% confidence intervals. However, unlike in the previous five hard and soft releases in the Upper Spray Wetland, a rapid decline in abundance of the Kihansi Spray was not observed until after month 4. In an expanded study, 701 animals were individually marked and released in May 2018 in Enclosure 2 in the Upper Spray Wetland. In this study animals that were treated for intestinal parasites 6 weeks after release or were treated after both the first and sixth week after release had significantly higher weekly apparent survival than animals that were not treated or were treated only after the first week. This expanded mark-recapture study also revealed no significant difference in weekly apparent survival between (1) animals raised in captivity in the Toledo and Bronx zoos; (2) between gravid and non-gravid females; and (3) by body mass (i.e., age class) after accounting for treatment for intestinal parasites.