larval behavior

When my larvae have empty guts they seem to move about more in a less organized manner. When fed up they settle into a tight school and just orent into current. Any see that with minnow larvae?

Yes I see that with the SRBD fry.
When hungry they seem to randomly roam about in uncoordinated fashion.
With full tummies they school up and face into the current.

I also notice a correlation between size and current.
The larger, more robust fry seem to like to be in stronger current while the runts stay in the eddies and quieter flows.
It's interesting because I notice the fry in the stronger current get more food and get it sooner. Therefore they are larger and more robust.
So do the runts seek low flow because they're weaker? Or are they runts because they choose to stay in the low flow?
Are the larger ones able to deal with strong current because they're robust? Or are they more robust because they choose the stronger current?

Yes I see that with the SRBD fry.
When hungry they seem to randomly roam about in uncoordinated fashion.
With full tummies they school up and face into the current.

I also notice a correlation between size and current.
The larger, more robust fry seem to like to be in stronger current while the runts stay in the eddies and quieter flows.
It's interesting because I notice the fry in the stronger current get more food and get it sooner. Therefore they are larger and more robust.
So do the runts seek low flow because they're weaker? Or are they runts because they choose to stay in the low flow?
Are the larger ones able to deal with strong current because they're robust? Or are they more robust because they choose the stronger current?

I am seeing the pattern in sunfish although I have not seen segregation based on size. Either the current is not strong enough or social hiearchy not established until some time after metamorphosis.