Fish that pilot Caribbean Reef sharks

Hey guys

Can anyone help me with an identification of this please?

They are quite common around Sint Maarten as fish that lead Caribbean Reef Sharks- but they clearly aren't Pilotfish. Some sort of Runner maybe? The markings are distinctive enough but I've been through the usual ID books a number of times and have drawn a blank so far.

Thanks

Juv. rainbow runner?

Thanks, Alex. Yeah I was thinking along similar lines. I thought it’d be easy to ID them but not so far. 

Here's the pic in full for a size comparison! 

This is not an usual sight here.

I've just found some pics of a juvenile Rainbow Runner and it does indeed look like that.

Google has these fotos of the adult Rainbow runner.

Is there a fish in that top photo?????

Thanks, Elias!

This photo, courtesy of Google, shows the Rainbow Runners to better advantage: