I'm not sure how conclusive the evidence is based on the article.
For an example of one of the classic kinds of "debunking" that this kind of research tends to get, see "Neural correlates of interspecies perspective taking in the post-mortem Atlantic Salmon:
An argument for multiple comparisons correction" ( http://prefrontal.org/files/posters/Bennett-Salmon-2009.pdf, PDF)
"The patients were repeatedly asked to imagine playing tennis or walking around their home. In healthy volunteers each produces a distinct pattern of activity, in the premotor cortex for the first task and the parahippocampal gyrus for the second. It allowed the researchers to put a series of yes or no questions to severely brain-injured patients. A minority were able to answer by using the power of thought."
So, I imagine they could say "To answer YES, imagine playing tennis. To answer NO, imagine walking around your home". Then they could ask yes/no questions and monitor the patterns of brain activity.
not sure if that is humour or real? If real that's really interesting. Redefines the idea of a dead fish really.