Heavensward Fishing Finds!

[Lyrinn]

Coerthan Crab (for level 50 leves) can be mooched off of Abalathian Smelt at Riversmeet. Also straight catch with Stonefly Nymph.
Blueclaw Shrimp (for level 50 leves), straight catch at Tailfeather using Stonefly Nymph, 100% catch rate (as far as I can tell).
Cloudfish (for level 52 leves), straight catch at Voor Sian Siran using Stonefly Nymph.
Grass Carp (for level 52 leves), straight catch at The Hundred Throes using Stonefly Nymph.
Icepick (for FSH 53 quest), straight catch at Unfrozen Pond using Stonefly Nymph.
Buoyant Oviform (for level 54 leves), straight catch at Cloudtop using Red Balloon.
Mahu Wai (for level 54 leves), straight catch at Cloudtop using Red Balloon.
Shadowhisker (for FSH 55 quest), mooch off of Blueclaw Shrimp at The Hundred Throes.
Letter Puffer (for FSH 58 quest), mooch off of Sky Faerie (straight catch with Red Balloon) at Landlord Colony.

Blue Cloud Coral (crafting mat), straight catch, snagged using Red Balloon at Cloudtop.
Gloaming Coral (crafting mat), straight catch, snagged using Red Balloon at Landlord Colony.
Mogpom (crafting mat), straight catch at Greensward using Goblin Jig, 100% catch rate.
Sweetfish (crafting mat), straight catch at Thaliak River using Goblin Jig.

Warmwater Bichir (collectible), straight catch at Smoldering Wastes using Purse Web Spider. Possible time window.
Weston Bowfin (collectible), straight catch at Weston Waters using Goblin Jig. Possible time window. No bites from 12 pm to 12 am.
Illuminati Perch (collectible), straight catch at Thaliak River using Goblin Jig.

[Lahdi_Oolong]

More exploration now that I hit 51. Using Stonefly Nymph

South Banepool:
Ice Fairie: Can be mooched with but doing so at 6pm in a Blizzard = Nothing Bites.
Seema Patrician can be caught straight as well as off the smelt mooch.

Unfrozen Pond: Ice fairie mooch is also "nothing bites" at 1am, Blizzard. Also, the Icepick is collectable.

9:50 am, blizzard: caught a Sorcerer Fish unmooched with Stonefly. This would seem to confirm that the restriction is time, not weather.

West Banepool (Western Highliands 13, 9). Requires the Stonefly Nymph or better to catch anything.

Ice Fairie - Mooch to Mercy Staff (lv 55, 8pm, Blizzard) and Fanged Clam (lv 52, 9pm, Blizzard). Can not seem to catch anything else with the Stonefly.

Edit to add: Greytail Falls Glacial Core mooch: Rime Eater, lv 55, 9pm snow.

edit 2: Wilhom River: Bluetail Shrimp mooch, 4am, thunder, "Nothing Bites", 6am, Nothing. 8am, transition to clear skies: Nothing. Nothing at 9 and 10am. Nothing at 12pm.

edit 3: Got it. Wilholm Catfish mooch off of blueclaw shrimp: 4pm, dust storms.

[Zorlinta]

Blueclaw Shrimp (for level 50 leves), straight catch at Tailfeather using Stonefly Nymph, 100% catch rate (as far as I can tell).

its just blueclaw when not use snagging, else you can get rock mussel and whillom catfish

also
West Banepool (Western Highliands 13, 9). Requires the CADDISFLY LARVA (lvl 50 bait) or better

[tomtensfarfar]

Weston Bowfin (collectible), straight catch at Weston Waters using Goblin Jig. Possible time window. No bites from 12 pm to 12 am.

During what weather did you find them? Cause i can't seem to get any, or they are rare.

[Lyrinn]

During what weather did you find them? Cause i can't seem to get any, or they are rare.

They were common when I caught them but they stopped biting after a while, which I assume is because the window closed. I didn't record the weather but haven't gone back since. If I had to guess, possibly Umbral Static. All I can confirm is what you've already quoted.