That's a betta, the fish Ambi mentioned. Interesting fact about bettas: they have a sort of nostril on the top of their head that allows them to surface and breathe air when the water they're in doesn't have enough oxygen to keep them alive-- at least that's what the guy at the pet store said when my mom commented on how small the plastic container things are that they keep them in. He probably pulled that one out of thin air.
I love salmon. They're cool to look at
BAM! and very tasty. The lengths to which they go to propagate are amazing, and they carry a great amount of cultural and mythological significance among the Native Americans of the Pacific Northwest. They are undoubtedly my favorite fish. I recommend baking salmon with lemon pepper and lemon slices. Or, for a neat-o school project, raise salmon eggs and release the tiny baby salmon into a river! Whee-ooh!
W00t! Mudskippers are real swell, too.
Gulper eels are great in their mystery and utter disgustingness.
Angler fish are awesomely scary and ugly, and
coelacanths are interesting in that they've been around for over 360 million years (that predates the dinosaurs, all you non-Dipstikk people), and were believed to have been extinct until 1938. More stuff about them
here, but I need to end this post before I get REALLY pedantic.