Fish Identifier Apps (2026): 10 Compared

Whether you've just landed something on a riverbank or spotted a flash of colour on a reef, the question is the same: what fish is that? Field guides help, but flicking through pages with wet hands isn't much fun.

Fish identifier apps compare your photo with thousands of species and suggest a name. The ten below cover anglers, divers, snorkelers and aquarium keepers, and several add catch logs or local rules. They're listed alphabetically and in no particular order, and each description comes from the app's own website or store listing, read this week. Planning a trip around the water? My ChatGPT prompts for planning travel will help with the rest of the itinerary.

Fish identifier apps side by side

I checked the free plan column on each app's own website or store listing, as of Oct 2026. Yes means the page names the app, an account or a plan or version of it as free. Trial only means a time-limited trial or demo. Not stated means the pages I read named neither, even where there's a download button or a free first scan, so check before you commit.

Tool	Type	Good for	Free plan
Fieldbook	Nature journal and ID app	A catch log with GPS	Not stated
FINS	Fish ID and dive log app	Divers and snorkelers	Not stated
Fish Rules	Fishing regulations app	Whether you can keep it	Not stated
Fishbrain	Fishing app and community	Catch locations and local reports	Yes
Fishial.AI	Open fish identification project	Supporting open fish ID research	Not stated
Fishium	Android fish identifier	Aquarium hobbyists and divers	Not stated
FishVerify	Fish ID and regulations app	Size and bag limits after an ID	Trial only
iDfish	Australian fish ID app	Offline ID in Australian waters	Trial only
Lens AI	Photo identification app using AI	Tropical and aquarium fish	Yes
Seabook	Fish ID and dive log app	Sightings from a boat or shore	Yes

Ten fish identifier apps to try

Fieldbook

Best for: Anglers who want every fish they identify saved as a journal entry with photos, GPS location, date, size, conditions and bait.

FINS

Best for: Divers and snorkelers who want to identify marine life, log dives and plan the next underwater trip in one field guide.

Fish Rules

Best for: Checking at a glance if a fish is in season, how many you can keep and how big it must be, using your phone's GPS.

Fishbrain

Best for: Finding spots with catch locations, depth charts, local fishing reports and regulations, next to a log of your own catches.

Fishial.AI

Best for: People who care about conservation and want to use, or contribute to, the largest open-source fish species image library.

Fishium

Best for: Curious anglers, scuba divers and aquarium hobbyists identifying thousands of species and reading about life beneath the surface.

FishVerify

Best for: Anglers who want a species ID plus local fishing rules and size or bag limits, so they stay legal on the water.

iDfish

Best for: Australian anglers who want offline photo ID, a guided flow-chart and size and possession limits for every Australian state.

Lens AI

Best for: Aquarium keepers and pet-store shoppers telling apart tropical fish whose colours and juvenile patterns can look alike.

Seabook

Best for: Linking each species to the moment you saw it, whether on a dive, from a boat or at the shoreline, with offline saving.

Which app fits where you fish or dive

• Checking if you can keep a catch: Fish Rules.
• Divers logging what they saw: FINS.
• Fishing in Australian waters: iDfish.
• Aquarium and tropical fish: Lens AI.
• Finding spots and local reports: Fishbrain.

When you need a rod licence in England and Wales

GOV.UK says you must have a rod fishing licence for England and Wales if you're fishing for salmon, trout, freshwater fish, smelt or eel with a rod and line. That includes fishing on private land, such as angling club waters or private lakes, and you also need permission from the land or fishery owner.

Children under 13 don't need a licence, and junior licences for 13 to 16 year olds are free. So knowing the species is only half the job: the licence depends on what you're fishing for and where, and many anglers wrongly assume private water doesn't count.

How to photograph a fish for a better ID

1. Lay the fish flat on a wet surface, side-on, and work quickly.
2. Make sure the fins, tail and any markings are fully visible.
3. Take one wide shot and one close-up of the head and mouth.
4. Note the location and whether it's fresh or salt water.
5. Return the fish promptly if you're not keeping it.

Anglers, divers and aquarium keepers need different apps

Anglers usually want an ID plus the rules: whether the species is in season, how many they can keep and the minimum size. Apps that combine identification with local regulations save a lot of searching on the bank or the boat.

Divers and snorkelers care more about logging sightings and depth, often offline on a boat. Aquarium keepers need help with tropical species whose colours and juvenile patterns change as they grow. Pick the app that matches where you'll use it most.

Fish ID mistakes to avoid

• Photos of a fish held up by the tail. The shape distorts.
• Trusting a match for a protected species. Check local rules first.
• Ignoring juvenile colouring. Young fish can look like another species.
• Relying on signal at sea. Choose an app that works offline.

What to check before you take an app on the water

• Does it work offline on the water?
• Does it show size and bag limits where I fish?
• Can I log catches or sightings with location?
• Does it cover fresh water, salt water or both?

Signs a fish ID is right

• The species lives where you caught or saw it.
• Fin shape and markings match the description.
• The size fits the species' normal range.
• A second app or guide agrees.

Do you make fish identification or fishing apps? Tool makers can ask to be considered for a featured place on this list.

My plain advice on fish identifier apps

Pick the app for where you spend your time: rules for anglers, logs for divers, tropical species for aquarium keepers. Take a clean side-on photo, check the suggested species against its lookalikes, and follow the local rules before you keep anything.

And if you're heading off to fish somewhere new, pack light; my guide to the best travel backpack helps with that.

Frequently asked questions

How do fish identifier apps work?

They compare your photo with images of known species and suggest likely matches, often with habitat and size facts.

Are fish identifier apps free?

A few apps on this list name a free version or free download on their own site, as the table shows.

Do fish ID apps work offline?

Some do, which matters on boats and remote banks, so check before you rely on one.

Do I need a fishing licence in England and Wales?

GOV.UK says yes for salmon, trout, freshwater fish, smelt or eel with a rod and line, from age 13.

Can an app tell me if I can keep a fish?

Some apps show local size and bag limits, but always check the official rules where you fish.

What's the best photo for fish ID?

A side-on shot with the fins and tail visible, plus a close-up of the head.