small phototropic critters....

its the second time i see this, the first time was well over 6 months ago.

this is how it happened.... this morning i turned off my system (pumps, filters etc, but not the lights) as i performed my weekly water change. i went down stairs filled up my 20 litre canister with nice fresh salt water and slaved it up the stairs...

as i was about to siphon its content in my tank i noticed these little guys (see picture) floating on the surface, moving about like little bugs would. granted the picture really sucks but i can tell you they are quite rapid in their movement, you can see in the picture that i barely had enough time to snap the shot as they were already all swimming towards the light i placed near the plastic container.

when i first witnessed this i though they may have been shrimp eggs (they roughly match the size of a cleaner shrimps egg), but seeing as i have no shrimp I'm at a loss.

hopefully someone has an idea....