In my aquarium, the fish are driven by the smooth seconds tag #DWFSS#. Each fish moves at a different speed but at least 5 or 6 times the speed of DWFSS.
The equation above sits in the X-position for one of the fish, instead of a constant as @Mellin pointed out. The equation goes something like this...
a. There are 320 units (pixels) in the creator screen and there are 360 units (degrees) in DWFSS before it resets to zero. 320 doesn't equal 360, but it's close enough for the task at hand. My fish start and end slightly off-screen anyway so the difference doesn't matter.
b. In this equation this fish starts when DWFSS > 110, around 18 seconds into the minute. When the fish begins it's cross, I need it to start at zero, not at X=110. That's why I'm subtracting 110 from DWFSS.
c. If you drive an object across the screen at DWFSS speed, it's painfully slow to watch but I want it to be smooth. To speed this fish up I'm multiplying by 8: ((#DWFSS#-110)*8). All the other fish have different speeds.
d. Once the fish swims off-screen I dont care what the value of DWFSS becomes, you cant see the fish anymore anyway.
e. Lastly, While the fish is waiting to cross (DWFSS is not 110 yet), the fish waits off-screen at 400 (x=400 in the equation). As soon as DWFSS hit 110, the fish comes back to x=0 and begins the crossing.
So my fish start at all different times and cross at all different speeds. Also, I'm not using the transparency feature at all. All of the fish waiting to swim across are just waiting off-screen at X= something higher than 320 where you cant see them. Hope that makes sense.