The aquarium companion that thinks. Log a water test and get plain-English grading against your fish's real needs. Check stocking, catch compatibility conflicts, schedule maintenance — and now track all 9 parameters on a real history chart, monitor your nitrogen cycle as a new tank establishes, and log tests faster with smart pre-fill. All offline, no account, one price.
See any of your 9 logged parameters — pH, ammonia, nitrite, nitrate, temperature, GH, KH, salinity, phosphate — plotted on a real line chart over 7 days, 30 days, 90 days, or all time. Spot trends, outliers, and gradual drift that a list of readings can't show. Includes min, max, and latest readouts beneath the chart.
Setting up a new tank? Gillwise now reads your ammonia, nitrite and nitrate history and tells you exactly which phase of the cycle you're in — Ammonia Spike, Nitrite Spike, or Cycled — with plain-English guidance for what to do next. Shown automatically for tanks under 6 weeks old. The single most valuable tool for beginners starting their first tank.
When you open "Log water test," Gillwise now pre-fills every field from your most recent reading. Just change the values that shifted — your stable ammonia 0 and nitrite 0 are already there. A banner tells you when pre-fill kicked in so you always know what came from your last test vs. what you entered today.
Enter your current nitrate (or pH, GH, KH, or salinity) and your target. Gillwise calculates the exact percentage and volume to change, the value you'll land at, and a 3-step gentle plan when a single large change would shock your fish.
Tap Export CSV in any tank's Water tab to share your complete reading history as a spreadsheet. Open it in Numbers, Excel, or any data tool. All 9 parameters plus notes, in chronological order.
An offline reference for 12 common diseases — Ich, Velvet, Fin Rot, Dropsy, Brooklynella, Swim Bladder Disorder, Hole-in-the-Head, and more. Symptoms, causes, first response, prevention. Searchable by symptom or name.
Log ammonia, nitrite, nitrate, pH, temperature, GH, KH, salinity and phosphate. Instead of just storing numbers, Gillwise grades every reading good, caution, or action-needed — measured against the overlapping needs of the species actually in that tank, not a generic chart. Each parameter gets plain-language guidance. The new history chart lets you see any parameter's trend across any time window.
Build your stock list from a 145-species library of fish, invertebrates, plants and corals. Gillwise estimates bioload and checks compatibility automatically — fin-nippers with long-finned tankmates, predators with fish small enough to eat, shoaling species kept in groups that are too small, species whose temperature needs simply don't overlap.
Every entry includes temperature, pH and hardness ranges, minimum tank size, adult size, temperament, diet, care level and real husbandry notes — for freshwater tropical and coldwater fish, brackish and marine fish, shrimp, snails, plants and reef corals. Search by name, common name, or region; filter by type or water category.
Set up recurring tasks — water changes, water tests, filter rinses, substrate vacuuming, dosing — and Gillwise shows what's due or overdue at a glance. New tanks get a sensible starter schedule. An at-a-glance banner on the tank list shows everything due across all your tanks at once.
Gillwise keeps everything on your device. No account to create, no ads, no tracking, and your tank data never leaves your phone. It doesn't request a single permission. One-time purchase — no subscription.
Gillwise provides general aquarium husbandry guidance and is not a substitute for veterinary care or your own research into your specific livestock.