I sent this to Jim back in 2002, for fish behavioural / interaction ideas... So while you are all waiting for MA3, (and for those of us not lucky enough to be testers!), download from this link,
http://www.shef.ac.uk/uni/academic/N.../aquarium.html
(You may (like me) have to run it in compatibility mode if you are on XP or Vista).
Not pretty, but weirdly addictive, and when we do get to see MA3, it will be like switching an old black and white TV to colour!