Great Kiskadee

Thanks Gilma! Your question really made me research and learn a lot about both species. I checked through some photos online but, in the end, I referred to my trusted "A guide to the birds of Costa Rica" by Gary Stiles. There are many subtle differences between the species. However the two most distinct concerning this spotting are the following:
The white bar above the eyes in Flycatcher does not meet/connect at the back of the neck.
The bill of the Flycatcher is more convex instead of straight.
The sunlight from the setting sun gives the appearance that the bill is a little broader and therefore may lead to the spotting I.D. mistake. However, the white bar above the eyes that meets at the back of the neck is definitive proof that this sighting is indeed the Great Kiskadee. Thank you so much for questioning the spotting. Now, out in the field, I will have a better grasp for distinguishing the two!

I am not an expert, but I thought I mention my observation.
I also have a spotting of a Great Kiskadee, http://www.projectnoah.org/spottings/154...
Looking at this one it seems to have a bigger/wider beak, that will make it a Boat-billed Flycatcher - Megarynchus pitangua,

Thanks Nuwan!

great shot!

thanks Atul!!!!

lovely !

I have seen them do it as well next to my home in a creek bed that is drying up.

I was not joking! This one is one of the only "songbirds" in the neotropic area which are catching smaller fishes besides all the rest of insects and small lizards.

Yes, fishing! ;-)

Cool! I wonder if the shape of its beak it is useful for something in particular

Thanks Alice!

Lovely!