This paper present data about digestive tract morphometrics variability of nase (Chondrostoma
nasus) collected from rivers Vrbas and Una (Sava catchment area). Total body length, standard body
length, maximum body high, body weight and digestive tract length and weight were measured on 60
individuals of nase (35 individuals from the river Vrbas and 25 individuals from the river Una). In order
to obtain data for body condition state and trophic state, Fulton’s condition factor (K) and Zihler’s or
intestine length weight index (ILV) were calculated. Higher values of length and mass of the digestive
tract were noticed for nase from river Vrbas wherein the statistically significant differences are identified
for the digestive tract length (p=0,015) and digestive tract mass (p=0,000). Also, a higher average value
for relative digestive tract length in comparison to the standard body length has been noticed for nase
from river Vrbas (2,7:1) in relation to those from river Una (2,5:1). There is a positive correlation (>70%)
between the standard body length and digestive tract length, as well as for body mass and digestive tract
weight. High values of Fulton’s condition factor indicates good physical conditioning of fish (K>1), and
Zihler’s index categorized nase as a typical herbivore species.
