Abstract
The diet and food niche overlap of five fish species in the Upor brook was evaluated. The supply of food represented by benthos was studied, and the proportion of total food particles in the intestine of brown trout Salmo trutta L., chub Squalius cephalus (L.), dace Leuciscus leuciscus (L.), bullhead Cottus gobio (L.) and stone loach Barbatula barbatula (L.) was measured.
Evaluations were performed using a new index (Mtot(p)). All fish species except stone loach exhibited a balanced consumption of the food supply.
The food components were systematically grouped, but no differences in the ingestion of these groups were found. However, a new approach in the evaluation of food competition based on observation of species-specific preferences/avoidance in ingestion of food particles was applied.
The particles were divided into four ecological categories according to their availability for fish. Brown trout concentrated on easily accessible sources of benthos or that hiding below stones, and also distinctly preyed on terrestrial insects.
Chub displayed a similar feeding habit, though concentrating more on drift and allochthonous sources. The food spectrum of dace was mostly composed of easily accessible benthic organisms, consuming fewer hidden benthos and terrestrial insects.
The food of bullhead and stone loach was similar, both preferring benthos. Bullhead consumed hidden species while stone loach consumed more accessible species rather than hidden ones.