After following the http://www.creationkit.com/Bethesda_Tutorial_Optimization I started noticing that were I to leave the roombound (without leaving the cell) the fish were in, depending on where else I went/which directions I looked in, when I returned to the aquarium only a few (or none) of my fish would remain.
I'm pretty sure I'm using all the vanilla spawn scripts but I'll update this post in a sec with the scripts. Any idea how to get my sweet little fishies to stay put/*persist??
http://i101.photobucket.com/albums/m57/will_cuthill/Mzandahrk/ScreenShot843.png.