These 33 out of 35 are all the fish I have found so far. I got tired of there not being a guide showing all the fish, so here is one in progress. While the written guide will have all 35, I have yet to capture the last two to put the images here. There will also be a video provided at the bottom.

Just a quick tip, basic fishing rod can only do so much. Get the lonely fishing rod from the Horns of the South area by the Ancient Cromlech teleport.

You can tell which fish you are getting via five markers:
1: The first being the bobber size in which they can be large, medium, or small.
2: The second being the bobber speed, in which how fast it goes up and down the channel.
3: The third being the behavior of the bobber in which it stays up or down or moves up and down repeatedly.
4: The fourth being the catch rate or the bubbles on the left. Some of the more rare fish take longer when trying to capture them compared to the usual suspects.
5: The fifth could just be paranoia after staring at these for hours, but the stamina bar or the Durability seems to drain faster for the rarer fish when not within the bobber.

While this guide won't cover these markers and the related fish, it is something to keep in mind when seeking these fish out during your game.

So starting with each area, I will list the location and time period in which I first saw these fish appear. Obviously some fish can be caught at different locations or time, but I only care about finding them once.

Horns of the South

Sunken Village Area:
Blake Sole-Day
Fluke Fish-Day
Turbot-Day
Crab-Day
Hooknose-Day

Left of the Ancient Cromlech:
Redfin Carp-Day
Perch-Day
Pike-Day

Roscree:
Weather Fish- Night
Gudgeon- Day
Common Barbel- Day

Village:
Plaice Fish- Night
Finnock- Night
Bull-Rout-Day

Under-All Mother Temple:
Saithe- Night
Mackeral- Day
Devil Fish- Night *Contributed by .ReЯik.*
RockFish -Night *Contributed by .ReЯik.*
SunFish - Day *Contributed by .ReЯik.*

Dead-Fisherman Rock:
Tunny -Day *Contributed by Bing! Game Guides.*
Blood Lake:
Sea Lamprey- Day/Night

Peninsula:
Tubefish -Day

Two Honorable mentions are

Quest Island for Cheese Spell which has the Really Special Herring regardless of time. Plus Big Coin Purses (25 coins), and trash like vase, mugs, etc.
Castaway Cave by the All-Mother Temple has trash such as Cups, Water Pitchers, Amphora, Horseshoes, and Wooden Dolls.

In Cuanacht

Lake next to Corrupted Temple:
Crucian Carp- Night
Blue Bream- Night

Lower City River (Next to farmland travel point):
Burbot- Night
Avalon Eel- Night

River by the Croakmaw that can take your arm:
Sneep - Day *Contributed by Bing! Game Guides.

Ocean (Follow the river where your arm can be chomped and jump down the Waterfall):
Pilchard- Day
Common Bream- Day
Four Horn- Day

River by Wyrd Tower (By the Fae Merchant):
Bighead Carp- Day

In Forlorn Sword:

Lake of The Primordial Beast:
Spined Loach- Night
Peasant Carp - Day *Contributed by Acedia*

Capital Waypoint:
Tench- Day

This video is an excellent guide by Bing! Game Guides, in which he showcases not only where he got the fish, but also the bobber's and other markers to help you find the fish faster. Definitely a great video and should be used when trying to secure some specific fish.

This link goes to a post that has some information on fishing from Drake Ravenwolf. I think it has good information and as such, you should check it out!

https://steamproxy-script.pipiskins.com/app/1466060/discussions/0/591773674360543946/?ctp=5#c591774829119538455

Thank you for reading this guide, this is my first, and I know it is not fully complete. Please feel free to add any fish and their locations in the comments. I will add them to the guide and credit you.

Special thanks to:

.ReЯik. for finding the Devil Fish, Sunfish, and Rockfish!
Acedia for finding the Peasant Carp!
Bing! Game Guides for finding the Tunny, and Sneep!

Also thanks to:

Bing! Game Guides for letting me post his video on here!
Drake Ravenwolf for letting me post his information on here!