Variations in food habit of the Himalayan mahseer - Tor putitora (Ham.) inhabiting the Ganga river system in Garhwal region

Abstract

Investigations on the food and feeding habits were carried out on the
Himalayan mahseer with a view to provide information on how the habits of
the fish differ in different tributaries of the Ganga river system. Highest
percentage of insect larvae and n3rmphs was found in the stock of Nayar (72.1-
89.8 %) and Saung (76.0-92.0 %). In the Ganga, animal matter accounted for
40-100 %, while in the migratory stock of the Alaknanda it was 76.0-88.07 %.
Fish remains were more common in the Ganga stock (2.85-60 %), least in the
Saung (0.1-0.8 %) and none in mahseer from Alaknanada and the Nayar. Plant
matter (diatoms, green algae and macrophytes) ranged from 0-60 ; 6-20 ; 6.22-
19.3 and 4-8 % in the river Ganga, Saung, Nayar and Alaknanda respectively.
Organic debris contributed 6.3 ± 0.71, 3.6 ± 0.0 and 36.0 ± 0.2 % of the diets
in the Alaknanda, Ganga, Nayar and Saung respectively. On the basis of the
percentage composition of food the fingerlings exhibited a greater degree of
omnivorous tendency. However, RLG values (0.42-21.11) indicated their
carnivorous tendency. The juveniles and sexually immature individuals were
found to be carnivorous. The tendency of omnivorous diet persists in higher
age groups (6+). The RLG values increased with increasing length of the fish
indicating suitability of gut for omnivorous diet.