Experimental results of trials to assess non-native fish impacts on the diet and trophic position of native pond fishes using stable isotope analysis in outdoor artificial ponds dataset https://portal.medin.org.uk/portal/start.php?tpc=009_CEFASfc505595-b3c7-4c5a-a886-d955fa3fe04f These data derive from experiments carried out during the spring and summer months of two successive years (2014 and 2015) in outdoor experimental ponds previously situated in East Sussex. The aim of the experiments was to determine whether or not introduced non-native fish species have an adverse impact on the diet and trophic position of native pond fishes. The experimental set up was more or less identical in both years, the study species in 2014 being the North American centrarchid (freshwater sunfish), pumpkinseed Lepomis gibbosus, whereas in 2015 the study species was the cyprinid fish native to Continental Europe, the sunbleak Leucaspius delineatus. 20180119 20171218