SESONAL VARIATION IN THE NATUTAL DIET OF KHISHNI LIZA ABU (HECKEL, 1843) FROM TIGRIS RIVER, IRAQ

Abstract

:A total of 467 fish of Khishni, Liza abu (Heckel,1843) were collected to study their natural diets and its seasonal variation. Four stations at Tigris River between Wana (Nynawa) at North and Al- Zaafaraniya South of Baghdad; had been chosen for this research. The research showed, that fishes mainly consumed plant (51.8%) and fewer animals in origin materials (18.7%), proving that it is an omnivores fish. Green and blue green algae ranked first (19.6%, 15.6%, 22.1%) in the diet of fish during the study period, followed by diatoms (15.4%, 17.0%, 18.9%) and insects with their larvae (11.7%, 10.6%, 9.0%), while detritus ranked forth according to volumetric (V%), occurrence (O%) methods of analysis and ranking index respectively. Sand occupied about a quarter of the stomach volume during the study period, but wasn't treated as a diet. Fish were found consuming green and blue green algae (17.9%, 27.2%, and 33.1%), followed by diatoms and insects with their larvae during spring, however it mainly depended on algae (15.5%, 16.6%, 18.0%), diatom and zooplanktons during summer. Diatoms ranked first (18.5%, 17.5%, 21.6%) during autumn, followed by insects and algae, while algae came first during winter (14.3%, 20.2%, 21.3%), followed by detritus and diatoms this time. Green and blue green algae (19.7%, 21.7%, 26.5%), diatoms and insects larvae were the first three items in the diet of L. abu from north of Sammura barrage.Whereas, algae (16.7%, 18.1%, and 21.8%), diatoms and detritus were the main diet of fish from the south of Sammura, The research also showed that, the two length groups of fish (less and more than 150mm) almost consumed the same food. Algae ranked first in diets of the two groups (20.9%, 20.2%, 21.3%) and (28.2%, 17.8%, 27.0%) respectively according to the above three methods of analysis

Keywords

• liza abu