Plan
Work out what fits.Before you buy the fish.
Two tools settle the question that decides most beginner tanks, and both take about two minutes.
Most used
Stocking calculator
Bioload, swimming space and filtration, plus every pairwise clash with a plain reason and a fix for each one.
Open the calculator →
Guided
Help me choose
Five questions, then a complete stocked tank scaled to the size you actually have, with group sizes and compatibility already checked.
Start the finder →New here
First tank?Read these four, in order.
Setting up an aquarium, cycling it, and learning to read your water parameters are the three things that decide whether a first tank works. Everything else can wait.
How to set up a fish tank
From empty glass to running filter.
Read → Step twoHow to cycle a fish tank
The month that decides whether fish live.
Read → Step threeTrack water parameters
Ammonia, nitrite, nitrate, pH and what they mean.
Read → Worth knowingWhy a bigger first tank is easier
The counterintuitive one most beginners get wrong.
Read →Fighting algae instead? Start at the algae identification hub, or go straight to black beard algae, blue-green cyanobacteria or green water.
Know
Every fish, properly.Not a stock photo and a guess.
Temperature, pH, adult size, temperament, diet and who it can actually live with.
Reference
Species database
An extensive database of freshwater species, each with a full care sheet, in six languages.
Browse species →
Betta
Neon tetra
Check
Compatibility checker
Any two fish, drawn at true relative size, with the water, temperament and predation risk spelled out.
Check a pairing →
Sizing
Tank size calculator
Start from the fish you actually want and find out how much tank it needs before you buy the glass.
Size a tank →Fix
Something is wrong tonight.Start here, not in a forum.
Answer what you can see and work down to the likely cause. Every outcome is a real page, not a guess.
The hobby
What everyone elseis actually arguing about.
Fishkeeping advice lives in forum threads that run to four hundred replies. We read the ones that blew up and trim them to what people actually said, noting where the crowd lined up, where it fought, and how noisy it got.
Crowd thread digests
Every digest scored for agreement and noise, so you can skim the argument before you read it.
Read the digests → Water & cycleBest water for a fish tank
Tap against well against RO, the bottled-water spats, and where the thread genuinely agreed.
Read the digest → Water & cycleCycling a tank faster
Every shortcut people swear by, and which ones the thread actually backed up.
Read the digest →Learn
328 guides.The ones people read this month.
Carry it
The aquarium appfor the other six days.
The website plans the tank. The fish tank app keeps it alive: logging, scanning and reminding, offline, with no ads.
- Scan test strips with the camera. On-device, and free for life.
- Track parameters over time so slow problems surface before the fish show them.
- Identify species and illness from a photo, with treatment steps.
- Simulate an addition before you buy it: bioload, temperament, space.
- Care reminders tuned to your actual stock and volume.
See more of the app
Tank dashboards
Health score, bioload and what needs attention, in one screen per tank.
Parameter history
Trends over time, so a slow drift shows up long before it becomes a crisis.
Illness scan
Photograph a sick fish and get a likely diagnosis with step-by-step treatment.
Simulator
Add a fish on screen first and see what it does to the tank before you buy it.
Compatibility matrix
Every pair in your stock list checked at once, not just the obvious ones.
Aquascape
Photograph the tank and try a look before you strip it down and buy plants.
Trusted
