This study investigated the impact of a three-week pilot practicum experience in an Aquarium setting on secondary pre-service biology teachers' epistemologies and pedagogies of teaching and learning. A qualitative case study methodology was employed to examine the experiences, views of teaching and learning, and teaching development of a small cohort of pre-service teachers who participated in the practicum experience in the Aquarium as part of their teacher education program. All pre-service teachers in the cohort experienced profound changes in their views of what it means to teach and learn, gained confidence in their ability to teach, and felt empowered as science educators following their teaching in the informal setting. Participants developed broader views of education, increased understandings of the educational theories of constructivism and of "teachable moments", and broader skills of teaching K-12 students. The study illustrates the potential of re/forming teacher education programs to incorporate practicum experience that goes beyond classroom settings. (Contains 3 notes.)