It seems likely.   The antennae are highly segmented along the length with larger segments closer to the head.  It looks like you have the sclerite from the front of the dorsal side of the head.  There are 34 species in your part of the planet so narrowing down what you have might not be to challenging.    In the bottom photo near the bottom; 1/3 over from right......is that a pair of tarsal claws?  That would also point to Plecotera.

Thanks Declan that's really useful! I'm not actually planning to ID any further than Plecoptera.

Hi Catherine,

Certainly the remains of a plecopteran, but the numerous tubercles on the antennae in your first picture makes me think that it may not be a larva, but a pupal skin or even a subimago. Difficult to be sure, but my guess would be a species of Leuctra, maybe L. geniculata - it's a species of large particle substrates & pretty swift water. It it is a late stage pupa, the Dace may have eaten it in mid-water.

Cheers,

Richard

See if you can find a tarsus if it has three segments then you most likely have a stonefly. If it's not three segmented it's not a stonefly.

I would also guess, like Richard, that these are the remains of Leuctra geniculata. The knobs at the basis of the antenna are typical for this species; moreover the shape and the large size of the insertion point of the antenna on the head (picture 3) is also very typical for this species.

" it may not be a larva, but a pupal skin or even a subimago "

Pupa and subimago of plecopteran is something very new for science.

Actually this is aphid.

The other responses to this ResearchGate question collectively suggest uncertainty of the photographed prey. Having done much gut analyses on N. Am. minnows, the prey often are fragmented that way. But the same prey may be more intact in the guts of other fish families, or 1 could take invertebrate samples to see what intact prey look like. So it might be useful to create a key for such fragments, akin to what's been done for marine crabs:

Elner, R.W., P.G. Beninger, L.E. Linkletter, and S. Lanteigne. 1985. Guide to

indicator fragments of principal prey taxa in the stomachs of two common

Atlantic crab species: Cancer borealis Stimpson, 1859 and Cancer irroratus Say, 1817. Canadian Technical Report of Fisheries and Aquatic Sciences

1403: 20 pp. (http://publications.gc.ca/site/eng/456604/publication.html).

Belatedly, Bob Vadas, Jr.