So...I have 0 level fishing right now. I'm using a magic splintered fishing rod +15 durability.

But it seems I can also use a magical pine fishing rod (Skill rank req:5) +13 durability.

What rod should I use...? And with that rod, what level of fish should I fish for?

I don't know about what you should be doing, as I'm no fishing expert. But my lvl is 6 and I'm using a lvl 10 rod on lvl 6 fish.

Use a level 1 rod with 25 dura

Level 1 rod?

He means a splintered rod, the first one you posted. You generally want to stay in the level range that the fishing rods call for. You can use up 10 ranks in tiers higher than your current rank if I remember the math correctly (Rank 1 fishing means you would be able to use up to rods within rank 11 aka tier 3 elm rods). This may not be exactly right, but really would not be ideal as you don't have the "experience" necessary to maximize fishing with a higher tier rod.

As for the level of fish, just fish at what normally spawns for you. You will always fish a level higher than your fishing rank to gain prof. Going higher will take longer to catch fish, and puts your rods at risk. Just my recommendations.

this for the most part. i used to go higher if say i was rank 8 id fish 10 for the next tier fish drops and as long as u use the riggt tier rod with decent dura ull be fine