Just had an idea for an easy way to fish on multiple characters and though I would share it with everyone.

Bind a key to "Interact with Mouseover" for this I will use "="

Make the following command:

<<%$LeaderName%>>
KeyReset 1000
If %KeyCount% = 1
Hit =
EndIf
If %KeyCount% > 1
Macro /cast Fishing
KeyReset
Endif

Now all you need to do is is spread out your characters and start fishing whenever one of their bobbers bob mouse over it and double tap the key you bound that command to.