Fish are the most numerous group of vertebrates in the world. This article is aimed to present the volumetric study of air-bladder in a local fish- Bata, scientifically known as Labeo bata (Hamilton, 1822). The study was performed by anatomical dissection of184 fishes of Bata species with further macroscopic examination of air-bladders. The research showed that in investigated species this organ has significant differences and is composed of two chambers. The present study assesses air-bladder dynamics in natural occurring populations with the aim to examine volumetric relationship between air-bladder and body of the individuals. It is clear that the buoyancy provided by the air-bladder. Air-bladder volume is a mean 9.4% of fishbody volume. Evidence is given to indicate that this is quite large when compared with data ‘5% of fish volume for marine fish, and 7% for freshwater fish.