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276 species, about twenty compatibility rules, and one job: telling you what won't work before you buy it. Here's the whole thing in seven screens.
Start with your tank
Everything is checked against one tank. Pick a real one and it brings its footprint along, which matters more than the volume does. A tang needs somewhere to swim in a straight line, not just deep water to hover in.
The setup switches underneath aren't preferences. Each one changes what the engine will and won't flag.
Find the animals
The filters are all in plain language: temperament, size, swim zone, care level, diet, reef-safe, captive-bred, colour, where it comes from. One of them works backwards. Under Solves a problem you name the algae, and it names the animal that eats it.
Read one properly
Open any animal for the full picture, including how big it really gets. That one is measured against a AA battery instead of a number you have to imagine.
Hover to measureGrazes film algae all day and needs open water to do it. Hard words like herbivore explain themselves on hover.
Every species page also has a check-it-against-my-tank button, so you can test one fish before building a whole list.
Watch it fill up
Add an animal and it drops into a cross-section of your tank at the depth it actually swims. The water rises as the bioload does.
Good fitGreat fitCheck fitGreat fitWhat gets checked
Bullying, predation, same-genus clashes, territory, shoals kept alone, minimum volume, swim length, bioload, jumpers without a lid, venomous spines, care level against your experience, reef safety. Roughly twenty checks, running all the time.
Clown Triggerfish50 cm · aggressive
Green Chromis8 cm · peacefulWhere a real relationship between two species has been verified, that beats the general rules. And where the data on a species is genuinely missing, the check stays quiet. A false alarm is worse than no answer.
Pre-flight
One verdict for the whole list, laid out like a cross-section of the tank: surface, then mid-water, then bottom, then cleanup crew.
You can tell it you've fitted a lid. You can't tell it you don't keep corals after all, or that you're suddenly experienced. Those live in your tank setup, where changing them reads as correcting your profile instead of muting a red row. And the saved verdict always reflects the raw checks, never what you waved through.
Share and build
Save it, share it, or hand it straight to the builder, which already knows the minimum volume, the lid and the filtration your crew needs.
Pick the fish first. Build the tank to match them, not the other way around.
— the ReefPicker way