UPDATE:

When my base skill got to 300, I was successfully catching any kind of fish around 75% of the time.

I used the same pole (20) and baubles (75), so figure if you're somewhere around 400 after bonuses you'll be able to fish somewhat consistently by the bridge north of Allerian Stronghold in order to get the Darters and skill points we all so desire.

At 345 base skill with the pole and baubles I am currently catching any kind of fish around 85 - 90% of the time.

On a side note, if you're interested in fishing the raised water near Skettis in Terokkar, you'll need a really high skill to even cast.  At 330 base with BIFPole and baubles (425 total skill) it said my skill was not high enough.