Disclaimer: This is a repost of the post made on Reddit by EnigmaT1m

A Guide To Fishing: How To Catch All The Fish

I’ve spent the entire expedition compiling as much information as I could about fishing, trying to answer any question I could think of and I think I about have it down. There is a LOT to cover here so I will start off with some quick bullet points with some useful information to get started.

You can dictate the size of fish you will catch with 100% accuracy
Fishing from the top of your ship beats the skiff in every way
There are 8 fish categories, 7 biomes and 1 group that appears in all biomes
The 7 biomes are : Hot, Cold, Toxic, Radiation, Barren, Mega-Exotic and Lush/Humid
Fish from the autocatcher that you haven’t discovered will appear, but greyed out
‘Player leaving system’ can despawn fish that are about to bite, fish a few systems away
Day/Night/Storm bait are pretty pointless, you’ll catch condition specific fish naturally
Depth is indicated on the HUD on bottom left when line is cast

On to the details.

Dictating the size of a fish:

First we will divide the water into shallow (20-30u) and deep (50u+) In shallow you can specifically catch ONLY small or medium and in deep water you can specifically catch ONLY large or colossal. Here is how…

When you first cast your line you will see 3 fish appear, these are not cosmetic or just effects, they are giving you information. They are telling you the size of the fish that is about to bite.

If you see a small fish when in shallow water you will get a small fish every single time. The small fish spawns with 2 medium size fish. If you want a medium, cancel your cast before the fish bites, you have 3-4 seconds from when the 3 fish spawn. Recast and repeat until you find 3 medium fish, at which point you are guaranteed a medium fish.

In deep water your two choices are 3 large fish or 2 large and 1 colossal. If you see a colossal you will catch a colossal, if you want a large then cancel and recast.

Small (S) Medium (M) Large (L) Colossal ©

M M S = S
M M M = M
L L M = M
M M L = L
L L L = L
L L C = C

Simply put, the odd one out from the three is the one you will catch unless all 3 are the same size which itself is an indicator of size.

Ship>Skiff:

Simple really, the skiff looks cool but is just glorified storage. Stand on the back of your ship and fish away. The ship isn’t affected by the waves when you are standing on it and you can quickly pop inside if conditions get a bit too rough. If the skiff was more stable, offered some protection and was actually able to be driven it would be much better. You CAN move it while on it, but not far. Simply summon it again and place it nearby, it will drift over to where you selected… very slowly.

Fish categories and biomes:

When you look in the ‘Wonders’ section and scroll to ‘Fish’ you will see a catalogue of all the fish available, though they appear in silhouette until you catch them. There are 168 fish and 9 miscellaneous objects.

The 168 fish are divided into 8 biome categories (listed above) and each contains 4 fish rarities. Each biome category contains 21 fish:

Common - 3S, 2M, 1L, 1C
Uncommon - 2S, 2M, 1L, 1C
Rare - 1S, 1M, 1L, 1C
Legendary - 1S, 1M, 1L, 1C

Bringing in the autocatcher point from above; any fish caught in there, that you haven’t caught by hand, will appear in black & white instead of colour. To get the colour picture in your discoveries, catch the fish with your rod.

‘Player leaving system’ despawns fish:

Self-explanatory really. I have caught all the fish while in the expedition, I quickly realised that fishing in a heavily populated system sucks. Beyond the hundreds of bases and communication beacons being such a distraction I noticed something quite funky happening. Sometimes when I cast, the three fish show up as normal but before one bites, they vanish! It took me a while to realise but it was happening whenever a player left the system. Between casting and biting, the fish would vanish. Not 100% of the time I might add but enough to be irritating. I jumped a few hundred light years away and did all my fishing there.

Bait:

In my bullet points at the start of this rather longwinded post I stated that day/night and storm lures are pointless. They slightly increase the chance to get the fish that you will definitely catch with regular bait during those specific conditions. You will catch diurnal fish in the daytime with any bait, same with nocturnal fish at night and stormy fish in storms. The condition specific bait icreases the chances but to catch all the fish, you will get all the day/night/storm fish long before you get all the legendary fish without ever using that bait.

Are the bionic lures worth the ridiculous amount of resources required to craft them?

Yes but not straight away. Save them for when you have caught everything else. You will catch legendary fish with a variety of bait. Here is a list of all other bait that has caught a legendary fish for me:

Green, blue and purple rarity fish, mealworm, chum, processed meat, seivert beans (put gamma root in nutrient processor), the autocatcher and a hadal core.

The bionic lure will get you a legendary roughly one for every 25 lures used. It is best used when you only need 1 or 2 legendaries from any given biome. You need 1 small legendary? head to shallow water, use bionic lure and ONLY catch small fish using the advice from the first section of this guide.

One final thing, a warning if you will. You will grow to hate the sight of a Stonescale Shark. It’s a common colossal fish available in all biomes and you will catch a LOT, it sucks more than the rest of the common omni-biome fish because colossal fish take a bit longer to pull in. A lot of effort for this guy again and again and again.

If you made it to the end of all this, thank you. If you have any questions, ask away, I am off to bed but will answer in the morning.

EDIT to add things I forgot ecause I was tired when I wrote this, or things pointed out in comments.

You should be able to get 1 fish for every piece of bait you use. When you cast the fish will either bite right away or will nibble a few times. There is never more than 5 nibbles, the fish will ALWAYS bite on that 5th nibble (bumping of the bait). You only don’t catch a fish if you reel too soon or you stop reeling while pulling in the fish. Otherwise, use 50 bait, get 50 fish.
Use the terrain manipulator to deepen shallow water, thanks u/Scaly_Pangolin. (I just moved)
Discoveries in expedition don’t appear in colour on main save, catch them again. Thanks u/MikeEmpuria
Similarly fish discoveries are account wide not save specific. Find them all on one save? They will appear complete but greyed on other saves.
Fishing difficulty, how much time you have to catch the fish can be adjusted in custom difficulty settings. Thanks u/MisterDream
You can place a base computer on the skiff!!! Thanks u/Hopalongtom
Condition specific lures only increase chances within that condition. A glowing orb will not attract a diurnal fish unless it is also daytime. A shadow orb won’t find a noctrunal fish in the day and a mag lure won’t find a storm fish outside of a storm.

u/mithrin Gets a whole section with some great information regarding difficulty settings:

"One of the settings you can choose is to auto-catch fish. This doesn’t change how long it takes, what it does is once the fish stops nibbling and actually bites, it will automatically reel it in. While you have a cast in the water, you can’t move without pulling in the line, but you can do plenty of other things:

Summon a ship or exocraft (say to re-summon your skiff to drift about)
Access and move things around in your inventories
Recharge your hazard protection or other items

I like to hit up a fishing spot after collecting my frigate expeditions, and fish with auto-catch on while I sort out my inventory. Or go to my underwater Circuit Board farm, harvest all the plants, and then fish off the dock while I craft."