• Catch Tiny Carp minipets. Very rarely.
• Fish of the Day pool migrations in Pandaria.
• Pagle fish are at least twice as common.
• Excess Golden Carp replace junk in Pandaria.

For a description of all changes and additions, read Patch 5.2.

Context: An Explanation of Catch Tiers

Old Azeroth's open water catches are grouped into tiers. The Gazetteer identifies 6 specific Zone Groups - sets of zones with the same set of catches. Each Zone Group has separate coastal and inland catches. Two of those groups define their catch further, into four 6-hour time segments. Many named fish appear in more than one zone group, typically with different catch rates in each group. Each Zone Group has the same Zone Base Fishing Skill. There are a few exceptions to this pattern, like Northern Barrens' Deviate Fish, but generally Old Azeroth's open water catch adheres to these 6 tiered Zone Groups.

The new lands found in The Burning Crusade, Wrath of the Lich King, Cataclysm and Mists of Pandaria are organised slightly differently: Each expansion has one or two common trash fish, such as Golden Carp, which can typically be caught in every zone in their respective expansion's waters. In addition to the common fish, individual zones, or sets of zones, have different more valuable fish in their open water. There is a strong correlation between these groups of catches and base fishing skill of their waters, as in Old Azeroth. There are exceptions, and a few quirks, such as Northrend's coastal fish only appearing in coastal waters named something other than the zone name. But generally expansion waters adhere to this principle.

Now, it happens that (almost) all coastal waters in each expansion contain precisely the same fish. So for coastal waters we can construct a simple 10-tier structure of catches, where the first 6 tiers are Old Azerothian Zone Groups, followed by a tier for each expansion. Only the most common catches are listed below:

1. Zone Group 1: Raw Slitherskin Mackerel
2. Zone Group 2: Raw Rainbow Fin Albacore and Raw Slitherskin Mackerel
3. Zone Group 3: Oily Blackmouth and Raw Rainbow Fin Albacore
4. Zone Group 4: Raw Rockscale Cod and Raw Spotted Yellowtail
5. Zone Group 5: Raw Glossy Mightfish and Raw Spotted Yellowtail
6. Zone Group 6: Darkclaw Lobster, and Raw Summer Bass or Winter Squid
7. The Burning Crusade: Giant Sunfish
8. Wrath of the Lich King: Imperial Manta Ray, Moonglow Cuttlefish and Rockfin Grouper
9. Cataclysm: Deepsea Sagefish and Murglesnout
10. Mists of Pandaria: Giant Mantis Shrimp, Golden Carp and Reef Octopus

Outland has no coastal water, but Isle of Quel'Danas (added in the final patch of The Burning Crusade) does have coastal waters and fish.

Application: What's Happening on Darkmoon Island

When fishing open coastal water around Darkmoon Island, your personal fishing skill determines which tier of fish catches the water contains. The first 6 "Old Azeroth" tiers increment every 50 skill points (until 300), with each of the final 4 "expansion" tiers covering 75 skill points. All the coastal fish contained within the groups outlined above are possible to catch at their respective tiers, but only the most common catches are listed in the table below.

Further notes and observations:

• Only your personal fishing skill is relevant. As far as can be tested, Poles, Gear and Lures cannot be used to alter the catch tier. Trained rank is not relevant, only skill. For example, if your skill is 300, but you have not yet learned Master rank, you will still catch fish from the (300-375) Burning Crusade tier. However, the maximum possible tier does appear to be capped by your account's expansion: For example, a Cataclysm account cannot exceed the 450-525 tier, even at 525 skill (thanks techempage).
• Between skill 1 and 25 there is a chance of catching junk. The chance of catching junk decreases as your skill rises up to 25, suggesting that the water is set with a base skill of 25 - in spite of all the other changes which alter the role of skill.
• There is no overlap or gradual transition between tiers. The catch is strictly determined by the skill/tier combinations listed above. Fishing at the maximum skill in a tier will give the next tier's fish, except when fishing at 600 skill (since there is no tier after Mists of Pandaria - yet). The fish caught that takes you from one tier to the next (such as from 299 to 300 skill) cannot be looted: A catch from the lower tier will appear in the loot window, but attempting to retrieve the fish gives the error, "You can't loot that item now." The catch (loot) table has presumably changed from the point in time at which the catch was generated, to the point in time that catch should be possible to loot, exposing a logic flaw in the loot process.
• The Sea Pony may still be caught. I caught a Sea Pony from the Zone Group 6 tier, and caught it alongside another common fish catch. This suggests that the Sea Pony is not part of the core catch (loot) table for the tier, but is part of a secondary bonus (low chance or perhaps conditional) catch table set only for Darkmoon Island. Similarly, no Mimic Octopus were caught during 400 catches into Mists of Pandaria-tier waters at 600 skill. That implies Pagle fish are only part of a secondary catch table belonging to Pandaria, and not part of the base tier 10 catch table.

Implication: Another Change to the Role of Skill?

Some aspects of this new Darkmoon approach to the role of skill are incomplete or buggy. The change only appears to apply to Darkmoon Island, a rather private location for most of each month. All that suggests the programming and design is still evolving, and/or that we might never see this change on live realms.

If applied universally, the approach is flawed: There is no way to reduce an angler's personal fishing skill, but highly skilled anglers might sometimes want to catch lower-tier fish. One possibility is that the system will only apply up to a zone's native tier. For example, Outland waters would never yield anything higher than the Outland tier, so anglers could always return to Outland if they needed to catch Outland fish.

The main advantage of the change would be that new anglers could catch a wide variety of fish as they improved their fishing skill, without moving between different zones. Catching 1,500+ Golden Carp by developing skill in Pandaria is ruthlessly efficient, but exceptionally boring! Unfortunately while the Darkmoon system makes that training process more interesting, it doesn't fit with MoP's changes to Cooking, which allow new (high level) cooks to train their Cooking skill from 1 to 600 without using ingredients from previous expansions.

So perhaps any major re-working of pre-MoP fish catches also requires an overhaul of pre-MoP Cooking? There are no tangible changes to Cooking on test realms yet, but there are some oddities emerging: For example, over the last week characters' Cooking skill has been reset to 1. That could be an innocent bug, or it could point to something else being tested in private. Crafty, isn't it?

Update: When asked what the odds of a "revamp for fishing" were, designer Greg "Ghostcrawler" Street replied, "Odds are high, but not for 5.2." However, major changes to fishing were first discussed almost 5 years ago, so it may still be too early to gamble on something big in patch 5.3.

"Rare [Pagle] fish catches are essentially twice as good."

Update: On average, 4.4% of catches from both open water and pools in Pandaria will have a Pagle fish attached. Slightly better than twice, especially as this feels much less variable than the 1 or 2% in patch 5.1. Detailed catch analysis below:

There are 6 different groups of waters Pagle fish may be caught from: Each of the 3 fish may be caught from pools or open water. One specific type of water was tested to represent each of these 6 different groups. At least a thousand regular (non-Pagle) fish were caught during each test. The results are shown in the table below.

Note that Pagle fish are now caught alongside a regular catch. So in the first case, 1,018 regular fish were caught from Swarm of Panicked Paddlefish, and 45 of those were caught with a bonus Flying Tiger Gourami. Some Pool migartion pools were tested, but other observations suggest their contents are precisely the same as normal pool types, such as Krasarang Paddlefish School. Since Pagle fish are unique, every Pagle fish caught was immediately thrown back in, allowing further Pagle fish to appear. Unique fish would not appear if the same named fish was already in one's inventory. All open water testing was done with sufficient skill to avoid catching extra Carp (formerly junk).

Proportion of "Pagle Fish" by Water

Pagle Fish		Sample Water	Pagle Fish Catch	Total Regular Catch	Percentage of Regular Catch with Pagle Fish
Total/Average			275	6235	4.4%
	Flying Tiger Gourami	Pool (Swarm of Panicked Paddlefish)	45	1018	4.4%
		Open Inland Water (Townlong Steppes)	46	1017	4.5%
	Mimic Octopus	Pool (Reef Octopus Swarm)	43	1035	4.2%
		Open Coastal Water (Krasarang Wilds)	53	1103	4.8%
	Spinefish Alpha	Pool (Sha-Touched Spinefish)	45	1050	4.3%
		Open Sha-Touched Water (Kun-Lai Summit)	43	1012	4.2%

All the catch percentages shown above are between 4 and 5%. There is no evidence that any one Pagle fish is more common than any other.

There is a very slight bias towards open water catches: 4.5% average from all open water, vs 4.3% from all pools. This could be a statistical glitch. However, the pool data was gathered with an Ancient Pandaren Fishing Charm active, and it is possible that the Charm only affects the regular catch.

For example, with the Charm active, 20% of the regular catch will be 2 fish, rather than one. So when fishing pools, our Charmed loot window will have opened about 170 (a sixth) fewer times during each test than when fishing open water: 170 of those pool lootings contained two catches, rather than one, so we reach our thousand target with fewer loot windows.

• If the Charm also added 20% to the chance of catching a Pagle fish, this would make almost no difference to the proprtion of Pagle fish caught. Almost, because there would theoretically be a tiny chance of 2 Pagle fish appearing at the same time, which can't happen because they are unique.
• If the Charm only adds 20% to the regular catch, overall our pool sample would be 133 Pagle fish against about 2,585 possible lootings: 5.1%, which is considerably higher than the 4.5% open water figure we are trying to match.

So the Ancient Pandaren Fishing Charm probably does not explain the small difference in catch rates between open water and pools. And the Charm may indeed increase the chance of catching a Pagle fish from any one successful cast, although perhaps not by enough to offset the extra time spent moving and casting into pools. Probably and maybe because the sample sizes are too small to be sure. The theory that the Ancient Pandaren Fishing Charm adds to the chance of catching a Pagle fish is important, because it suggests that even rarer catches are influenced by the Charm. A 20% bonus when trying to catch a Tiny Red Carp or Sea Turtle could save a lot of time!

In practical terms, all this suggests that all sources of Pagle fish have identical catch rates. Charmed fishing of densely packed pools (such as those found during pool migrations) will be comparable to fishing open water with sufficient skill. The choice is yours.