Understanding the Nature of Science (NOS) is useful for pre-service, novice, and senior teachers. This strand is a fundamental concept in understanding science as a unity. This article utilizes a qualitative study, descriptive-interpretive approach of the effectiveness in learning about the NOS in relating to Pre-service Physics Teachers’ (PSPTs) voices on dynamic fluid. The approach was explicit and reflective. Two research questions were posed: (1) What conceptions of NOS do the PSPTs show regarding the fact, concept, principle, hypothesize, law, and theory of dynamic fluid?, and (2) To what extent do the PSPTs’ existing knowledge and reasoning of dynamic fluid?. A content analysis was considered in helping the researcher to better comprehend the process of constructing meaning. The study involved of an open questionnaire. A number of thirty one (31) PSPTs in public university in Surabaya Indonesia were invited to complete the questionnaire form. In presenting the results of research, the participants were coded by pseudonyms name with popular Indonesian nickname. The PSPTs’ voices were categorized into 4 levels:  dissatisfied (naïve), intelligible, plausible, and fruitful.