Modern Fish

[Agrus Kos, Enforcer of Truth]

I have been thinking of building modern fish, but now I have a few questions:

Which is better, mono blue or blue-white?
I have seen some lists with {Thassa, God of the Sea}, would I actually run her?
If I go mono blue, how many {Master of Waves} and how many {Nykthos, Shrine to Nyx} do I run (if any)?
What is a good number of {Cavern of Souls} for the deck?
What is the best counterspell for the deck? I have seen {Dispel}, {Remand}, {Mana Leak} and {Spell Pierce} run...

Looking for feedback from people who have run the deck and/or have a lot of experience in Modern. Thanks for reading and thanks for the help.

[DeathlyFoiend]

If you run Thassa, only run 1-2.
2-4 Master of Waves.
No Nyxthos.
Usually 2 along side 3 Mutavaults if you run any Caverns.
Spell Pierce, Mana Leak and Remand do different things, there is no one card that is better than others, they just want things to be done. Choose your poison.

[rarehuntertay]

In my fish, I run 3 masters, 4 vaults, 3 cavern. No nyxthos, it's not needed. I'm running one Thassa, but she's really not that important. I run 2-3 {spell pierce}. 1 cc counters are better for this deck than the 2 cc counters.

[Agrus Kos, Enforcer of Truth]

Thanks guys.