There is none there only old rod good rod and a super rod
super rod
In Pokemon Platinum the Good Rod is to the right of Hearthome City. The fisherman on Route 209 will give you the good rod.
Old Rod.
a good rod or super rod
You get the old rod to the left of jubilife city.
route 209
Magikarp
No
you use a super rod at iron island
Because platinum is non reactive metal
You can receive a Super Rod from a fisherman in the Fight Area on Pokemon Platinum, Diamond and Pearl.
In the Fighting Area, talk to the fisherman and he'll give you a Super Rod.