Biological conservation has a long story, but what distinguishes Conservation Biology from previous conservation fields is its multidisciplinary scope and its character as a mission-oriented crisis discipline. These characteristics suggested the introduction of the metaphor of biological conservation as a sort of surgery. This paper is about the initial stages of such surgery. Firstly, some data about the so-called "Big Sixth"—the disease—will be presented together with some information about Conservation Biology—the surgeon. Then epistemic and epistemological difficulties in extinction assessment and conservation prioritization, and triage in particular, will be pointed out. It will be argued that, while data deficiency arising from empirical and practical constraints can in principle be overcome, a different order of difficulties stems from the competition among several species concepts. In this case, it will be suggested that the extent of complications is of such significance to require a thorough re-assessment of the very nature of the patients, i.e., outside the metaphor, of the concept of species.