Free on the App Store for iPhone
Neptune learns which conditions your fish bite in, and works out how old the one you just caught is.
Saturday · Esopus Creek
Today's conditions score
Last trip
3h 42m5 fish · 2 species
Personal best
24.5″Brown Trout
Next prime window
Above your average catch density
Moon & pressure
Conditions forecast
Here's what happens to one fish, from the moment you log it to the point where Neptune knows how old it is and what the conditions were.
Log
Start a live trip and Neptune runs the timer, holds your location and keeps a tally while you fish. Log the species and length, then get back to casting.
5 fish · 2 species · 1 break
8:41 AM · dry fly
8:12 AM · nymph
7:38 AM · nymph
Enrich
Nobody writes down the barometer reading every time they land a fish. You type in two things; the moment you save, Neptune looks up the conditions at that spot and time and stores another fourteen next to them.
Catch detail
Conditions at catch AUTO
Location
Tackle
Notes
Riffle below the bend, third cast. Fish held tight to the seam once the light went off the water.
Year class
2020 · age 6Learn
Most apps count the conditions you caught fish in, which mostly shows when you go fishing. Neptune measures fish per hour fished against your own average, so the hours you blanked count too.
Conditions window
Catch rate · fish per hour fished
Now: 30.12 inHg · 1.8 fish/hr
Falling · 2.1 vs 1.1 fish/hr
90% interval 1.3-2.8 · 41 trips
52-56 °F · 1.7 fish/hr
90% interval 1.1-2.2 · 36 trips
No solid pattern yet
Intervals still cross 1.0×
Score
Neptune compares tomorrow's forecast with the conditions you've caught fish in and scores the day. The breakdown shows how many points each factor added.
Tomorrow · Esopus Creek
out of 100
Strong window
Conditions match · factors met
Peak 3 of 3 · 6-8 AM
Next 5 days
Best day: Wednesday
Alert
Esopus Creek · 7-day lookahead · quiet hours respected
Year Class
Say you catch a 19½-inch brown trout. Neptune works out that it hatched in 2020, that six is in the prime years for a brown, and that the same batch was stocked into three other waters within driving distance.
Biologists publish growth curves. Neptune runs one backwards: give it a length, get an age.
The year you caught it, minus its age.
Batches born within a year of your fish, searched across every water in the state.
39 species carry a curated trophy age window. Inside it, the fish is flagged PRIME.
Year class
19.5″ · Esopus Creek · 2026
Estimated age
6 yrYear class
2020Prime window · ages 5-9
Tier A · agency citation
Same cohort stocked at
Stocking history · Esopus Creek
Showing 3 of 12 recent records
Most age windows come straight from state and federal fisheries research: walleye 8-15 years, muskellunge 8-15, where the average one an angler catches is 11 years old and 45 inches.
When there's no published trophy age, Neptune works one out from the species' growth curve and labels it that way. Species with no window get no badge. Bait species like Golden Shiner are left out on purpose.
If a lake got a heavy 2020 stocking and that species peaks at ages 6-12, you know something concrete about the next few seasons there.
The same batch of fish, the same age, often went into water nobody is crowding.
Reorder them however you like. They're grouped into Charts, Intelligence and Records, and none of them use anyone else's data.
It plots fish per hour fished, so a blank morning drags the line down. You can read that rate four ways:
Every condition as a response curve with today's reading marked. If today is outside the range your log covers, the marker is left off.
Tiny through Trophy, ranked against your own catches of that species, so "trophy" means trophy for you.
What you're catching, and how the mix shifts by season and water.
Which lures, sizes and colours earn their place in the box.
Your most productive water, ranked, with per-trip stats behind each.
Moonrise, moonset, illumination and phase for your next trip.
Records per species, plus badges you earn: first 20″ fish, 100 catches, a 30-day streak.
Which of your catches trace back to a stocked cohort at that water.
Trips and catches as a sortable table with 30 selectable columns, saved views, and CSV export.
A widget carries the day's score. Start a trip and a Live Activity puts the timer and your catch count in the Dynamic Island.
A similarity engine matches waters on their characteristics and on what bait lives there, curated per state from agency reports. Stocking, regulations and habitat profiles sit alongside, on a clustered map that stays smooth at tens of thousands of pins.
Logging, conditions and your own stats work anywhere. State data gets added one state at a time. Here's where each piece is.
Full depth: stocking, regulations and survey-grade forage Logging, conditions and stats, with stocking and forage varying by state
A few things it won't do:
A screen recording gives your spot away in about a second. Incognito hides the water's name, the map and your catch pins for the whole trip.
The trip still logs normally. Incognito only changes what's on screen, and it has no way to touch what gets saved.
No ads and no social feed. Neptune is a private logbook that happens to be good at statistics, and your catches only feed your own stats.
Free. Requires iOS 17 or later. Covers 15 East Coast states at varying depth; full stocking, regulations and forage data currently covers New York, New Jersey, Pennsylvania and Florida. If something looks off, there's a Report a Bug button in Settings.