It is actually hard to tell without seeing the dorsal fin in that picture. But I am leaning more towards a sucker, than a carp, for two reasons. One, there aren't any wiskers, and the shape of the head.

have a look at top center here:

http://www.google.ca/search?rlz=1T4A..._t-amU#imgrc=_

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If you check a local fishery site, they should have pictures of the local variants of each in your area.

But the size and shape of the dorsal fin is really what differentiates the two