I thought I'd add this as well for anyone interested. I have been having great success with it lately. Just a simple use of an ice cream container and a cheap flash diffuser.
You can see the receiver mounted to the flash and the trigger that mounts to the cameras hot shoe sitting next to it.
I'm tracking the use of the slave flash, I use mine essentially the same way, but what's the point of the master speedlight? Is it actually used or was Xander simply mentioning that it is equipment that he has?
Three light setup with cyber syncs, for a long time I've used a Styrofoam box to reflect the light into the tank but always ended up with unwanted shadows, so tonight I played around with a lights a little bit and realized portrait photography can be used as well. Creating a rim light to fill the sides of the fish has yielded some very nice results.