Komposisi Pakan Ikan Gariang (Tor douronensis) Berdasarkan Isi Saluran Pencernaan di Sungai Batang Anai Kabupaten Padang Pariaman Sumatera Barat

Abstract

Gariang (Tor douronensis) is a high-value fish in West Sumatra whose wild populations are under pressure from habitat degradation and fishing. Its natural diet has not been described, although this information is needed for habitat management and domestication. This study described the food composition of gariang in the Batang Anai River, Padang Pariaman Regency, from digestive tract contents, and graded each food item with the Index of Preponderance (IP) as main (IP > 40%), secondary (4–40%), or complementary food (< 4%). Fifteen fish (210–355 mm total length) were caught in June and August 2019, but only six had food in their digestive tracts; the diet analysis is therefore based on these six fish. Fourteen food taxa from Bacillariophyceae, Cyanophyceae, Chlorophyceae, Rotifera, and detritus were found in the fish examined. At the food-group level, Bacillariophyceae was the main food (IP 77.03%), while detritus (16.44%) and Cyanophyceae (5.87%) were secondary. At the genus level no item exceeded 40%; Cymbella (36.67%), Synedra (21.70%), detritus (19.22%), Navicula (11.23%), Spirulina (4.85%), and Gomphonema (4.04%) were secondary items, and the other eight taxa were complementary. The diet of the fish examined was thus dominated by attached diatoms and detritus, indicating that they fed mainly on periphyton. Because periphyton availability in the river was not measured, it is not yet possible to tell whether the fish select particular diatoms or simply eat the most abundant ones. The mean relative digestive tract length (3.19 ± 0.84 SD; n = 9) is consistent with a plant-based diet but is not sufficient evidence on its own. Given the small number of fish with food, these results should be regarded as preliminary