I know that the Throwing stick (being one of humankinds oldest weapons/tools) was used for hunting birds and small game. But are their other forms or types of throwing sticks used for fishing?

I'm assuming you are referring to the boomerang-shaped throwing sticks similar to those used by the Egyptians for hunting as well as warfare.

Example: http://www.hickoksports.com/images/egypt_throwsticks.jpg

While I can't say with absolute certainty this type of stick was never used for fishing in any culture or situation, it seems the thrower would have problems getting the throwing stick to maintain enough speed to penetrate more than an inch or two of water before loosing the power needed to stun or kill a fish. I think different stick shapes (javelin or spear) would have proved to be more effective and that concept may be borne out by the way hunting and fishing methods of the Egyptians are described in their art.

The tomb of Menna, an Egyptian scribe, has wall panels depicting hunting marsh birds with throwing sticks and fishing with spears which don't appear to be thrown like a javelin, but held in the hands for control and power to penetrate the scales of a fish.

Throwing sticks: http://www.osirisnet.net/tombes/nobles/mena/photo/menna_cm78.jpg
Spear fishing: http://www.osirisnet.net/tombes/nobles/mena/photo/menna_j02.jpg