Feeding indices of Planiliza abu (Heckel, 1843) in Karun River, Southwestern Iran

The feeding characteristics of Planiliza abu in Karun River, Khuzestan Province, southwestern Iran were studied by collecting 460 specimens from November 2016 to September 2017. The specimens were anesthetized in 1% clove oil, fixed in 10% buffered formalin and transferred to the laboratory. The average length and weight of all specimens were 13.18 ± 1.35 cm and 31.05 ± 9.22 g, respectively. The average condition factor for both males and female was 1.34, exhibiting no significant differences in different months in both sexes (p > 0.05). The mean relative length of gut in all fish was 2.27 ± 0.36 during the year.  The highest gastrosomatic index (GSI) value was in September (12.07), while the lowest in February and March displaying significant differences in different months (p < 0.05). A total of 214 empty stomachs were found amongst the 460 fish samples and there were no significant differences in the ratio of empty stomachs in different months (p > 0.05). Therefore, based on the visual observations, RLG and GSI, it could be concluded that this species is an omnivorous fish (mainly aquatic insects and plants, algae, diatoms, and detritus) with a modest feeding throughout the year.