Free Printable Aquarium Charts (PDF): Fish Compatibility, Care and Cycling

Which aquarium charts can you download?

Three charts are available, and each file comes in two paper sizes so it prints without scaling on either side of the Atlantic. The table summarises what is on each sheet; the download links sit further down the page.

How does the compatibility chart decide each verdict?

Each mark on the compatibility chart is the verdict of the AquaCompat compatibility engine, the same fixed formula behind the online fish compatibility checker. For every pair, the engine compares published temperature, pH and hardness ranges, temperament, adult size (as a predation check) and swim level, weights those factors into a score, and turns the score into one of three verdicts. A few deal-breakers, such as two species with no shared temperature range, force an incompatible verdict regardless of the score. The weights, thresholds and hard fails are set out in full in our compatibility method.

The goldfish row shows how this works in practice. Goldfish are listed at 59–70 °F (15–21 °C), below most tropical species, so nearly every cell in that row reads incompatible; the betta and goldfish pairing is a typical example. A caution verdict means the pair can share a tank under conditions, for example a large enough tank, enough cover or a narrower water range. The chart does not say which conditions apply, so it is a first screen. Follow a caution verdict up with the betta tank-mates list or the matching tank-mates page, which explains each factor.

Where do the care chart values come from?

Every value on the care chart is copied from that species' sourced fact file, the same files that feed the species profiles and every verdict on the site. Those files draw on FishBase, Seriously Fish, PlanetCatfish, university extension services and peer-reviewed papers. Where sources disagree, the range shown is the consensus across them, not the widest figure any single source gives. Discus, for example, appears at 79–86 °F (26–30 °C) and pH 5.0–7.6, the same ranges used on the discus tank-mates page.

A dash or blank in a cell means the fact base holds no sourced value for that field, not that the value is zero. Lifespan is the field most often missing, because many hobby species have no published longevity figure that meets our sourcing standard. Group sizes are minimums for the animal's welfare, not stocking targets. Check a full stocking plan with the aquarium stocking calculator.

What does the nitrogen cycle cheat sheet cover?

The cheat sheet gathers the figures fishkeepers look up most while cycling a new tank, each tied to a named source. UF/IFAS and Merck put biofilter establishment at 6–8 weeks, and fishless cycling without a bacterial additive is listed at 30–45 days. SRAC 4502 sets a fishless starting dose of 3–5 mg/L total ammonia, and the sheet gives the toxicity thresholds for ammonia, nitrite and nitrate alongside it.

The second half covers water changes, from the routine 25% weekly change to the 25–50% change recommended when ammonia appears in an established tank. The sheet is a quick reference. The reasoning behind each number is in the nitrogen cycle guide and the step-by-step fishless cycling method.

Who are these charts for?

The charts are written for anyone planning or explaining a freshwater community tank:

• Beginners can pin the compatibility chart near the tank and check a new fish against every current resident before buying.
• Fish shops can post the chart by the sales tanks, so staff and customers start from the same published ranges.
• Aquarium clubs can hand out the care chart and cheat sheet at meetings, auctions and beginner talks.
• Teachers can use the cheat sheet in classroom tanks and biology lessons on nitrification, and the compatibility grid as an example of a decision matrix.

How should you print the charts?

Print at 100% scale, or "actual size", rather than "fit to page", which shrinks the small type on the compatibility grid. Choose the US Letter file in North America and the A4 file elsewhere. The compatibility chart and the care chart are landscape, so set the printer to landscape orientation, and print the care chart double-sided if you want it on one sheet.

The verdicts are printed as symbols with a key, not only as colours, so the compatibility chart stays readable on a black-and-white printer. For a tank-side copy, laminate the page or put it in a clear sleeve, since splashes ruin plain paper quickly. Check this page for a newer version now and then, because the charts are regenerated when a species fact file changes.

Can you share or republish the charts?

Yes. The charts and the species dataset are released under the Creative Commons Attribution 4.0 licence (CC BY 4.0). You may print, copy, post, translate, adapt and republish them, including in commercial settings such as a shop or a paid course, as long as you credit AquaCompat and link to this page. A suitable credit line is:

Chart: AquaCompat, "Free printable aquarium charts", https://aquacompat.com/free-charts/ (CC BY 4.0)

If you adapt a chart, for example by adding your shop's own species, say that it has been changed. Please do not present an adapted version as an AquaCompat chart. If you spot a value that looks wrong, send the species, the value and your source through the AquaCompat contact page, and a corrected chart will follow the corrected fact file.