If it is "stinky" then at least a significant portion (or all) of it is organic material.

Further, the fact that it is stinky means it is not being subject to decay in an aerobic environment.

I do NOT know how much aerating the pond will help with the pre-existing muck. (I think it is difficult to suspend off of the bottom.) However, I believe the experience of the people that have added aeration is that it will significantly reduce the future accumulation of muck if deployed correctly.

(You are properly posted in the aeration thread, so I am just giving you a little background info pending some actual experts dropping in.)