A common mistake I see in attempts to build fish decks is simply that many of them are nothing more than piles of hate and some guys rather than a
focused, coherent deck. People forget that fish is a
tempo deck, not a hate deck. While those two strategies do overlap sometimes, being able to distinguish between them is important to keep in mind while designing fish lists.
For reference, here is one list that I would consider a focused, coherent tempo deck - Eric Becker's URBana Fish, which has put up successful results in local tournaments (along with my testing and apparently his as well).
4 Polluted Delta
2 Flooded Strand
1 Swamp
2 Island
2 Underground Sea
3 Volcanic Island
4 Wasteland
1 Strip Mine
5 Moxen
1 Black Lotus
4 Gorilla Shaman
4 Ninja of the Deep Hours
3 Waterfront Bouncer
4 Dark Confidant
1 Ancestral Recall
2 Brainstorm
1 Time Walk
1 Mystical Tutor
4 Force of Will
3 Chalice of the Void
4 Duress
3 Mana Leak
1 Rack and Ruin
What makes this different from most other peoples' fish lists? First off, look at how many ways it has to replenish its threads and disruption that aren't potential card disadvantage (like Curiosity) or extremely clunky to play with (like Standstill):
4 Ninja of the Deep Hours (with eleven potential one-drops)
4 Dark Confidant
2 Brainstorm
1 Ancestral Recall
Eleven ways to draw cards or significantly improve card quality. This is rivals or even exceeds most modern control decks - even Rich Shay's Richmond list only had ten. This is important; what seems to happen in many of the fish matches I've played in tournaments is that my opponent would use his disruption to put both of us into topdeck mode, and then I end up coming back with ease due to my much greater card draw and overall card quality. These eleven cards are how URBana Fish solves this problem.
Another element of this deck's success is the quality, quantity, and efficiency of its disruption.
4 Gorilla Shaman
4 Duress
3 Mana Leak
3 Chalice of the Void
4 Wasteland
1 Strip Mine
3 Waterfront Bouncer*
1 Rack and Ruin*
This is
a lot of disruption, especially when you consider the amount of card drawing this deck has. Also, outside of the asterisked cards, all of this disruption is unconditional (more precisely, the conditions are nearly ever-present) and often has uses other than disruption (such as Gorilla Shaman being usable for ninjitsu). Note the absence of cards like Stifle, Misdirection, or Spiketail Hatchling here. The most notable absence is Null Rod, but not only does it adversely affect the deck's own mana base, but it would horribly crowd the two-mana slot in the deck.
0: 4 Wasteland, 1 Strip Mine, 3 Chalice of the Void
1: 4 Gorilla Shaman, 4 Duress, 1 Mystical Tutor, 1 Ancestral Recall
2: 4 Ninja of the Deep Hours (for all intents and purposes), 4 Dark Confidant, 3 Waterfront Bouncer, 3 Mana Leak, 1 Time Walk
Considering how well the deck can utilize Moxen to cast all of the deck's two-drops, running Null Rod probably wouldn't be very good for it. The Moxen allow the deck to drop power on the board almost as quickly as Meandeck U/W Fish, which is another reason the deck succeeds. I see many, many Fish lists with 4 Meddling Mage, 4 Mishra's Factory, and a bunch of one-power creatures. That is far, far too slow. This deck is regularly capable of 5-6 power worth of creatures on the board by turn three, something most Fish lists can't boast.
Try to find similar strengths in many of the other lists being posted around here or in those that failed to perform at Richmond, and you will almost invariably find that they are either lacking those strengths or do not have them to the same an extent as this one. The TMWA-style builds are the worst, because they are just ~37-38 hate cards and some mana sources.
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Re: Phyrexian Negator
While he is a serious clock and an efficient threat, the thing Fish wants to do the least is walk a three-mana spell into Mana Drain. As stated earlier, he also makes you extra-vulnerable to Triskelion. Two-power guys that either draw you more disruption or act as disruption themselves are better.
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P.S.
but frankly, there are builds of Fish out there that have good matchups against almost everything, INCLUDING OATH.
OMGWTF OATH IS THE BEST DECK IN THE FORMAT, NOTHING IS SUPPOSED TO HAVE A GOOD MATCHUP AGAINST IT