Behavioural strategies for feeding of six species of the Antarctic fish family Nototheniidae (Pisces, Notothenioidei) in a tank

Abstract

The feeding strategies of six Nototheniid fishes, Notothenia coriiceps, Notothenia neglecta, Trematomus bernacchii, Pagothenia borchgrevinki, Lepidonotothen nudifrons and Pleuragramma antarcticum, were studied in tanks, under controlled environmental conditions. These fish were caught in Admiralty Bay, King George Island, during the Antarctic summer. Although P. antarcticum preyed only in the water column, the remaining five species fed not only in the water column but also at the bottom. Persecutions of prey were observed in T. bernacchii, L. nudifrons, N. neglecta and P. antarcticum. The sequence for feeding always started from resting except for P. antarcticum and N. coriiceps. Each feeding sequence lead to the ingestion of one fish each time by N. neglecta, T. bernacchii and P. borchgrevinki, but N. coriiceps was able to catch and ingest several fish during one period of random swimming. Many krill and/or amphipods were usually ingested by all predators during one feeding action, but T. bernacchii also caught them one by one. T. bernacchii, N. coriiceps, N. neglecta and P. antarcticum sometimes rejected fish and/or amphipods after apprehension. The competition for food in the tanks seemed to be minimised by differences in feeding strategies.