Northern Map Turtle — care sheet

Intermediate. Not hard to feed or handle, but genuinely demanding on space and water quality. Map turtles are strong, active river swimmers who need a big, well-filtered tank with clean, oxygenated water, plus a proper heat-and-UVB basking setup. They're also famously shy and prone to skipping meals or hiding when stressed, so they reward a calm, patient keeper more than a fussy one.

Predominantly carnivorous, and mollusc-loving in particular. In the wild females crush snails, clams, and crayfish with their broad jaws while males take aquatic insects and smaller snails. In captivity, base the diet on a quality aquatic-turtle pellet (Mazuri, ReptoMin) plus whole prey — snails, earthworms, crayfish, krill, and the occasional feeder — with some leafy aquatic greens and plants offered too. Feed hatchlings daily; taper adults to protein 2-3x per week with more plant matter, to avoid overfeeding and shell/growth problems.

Think in swimming volume, not floor space. A single male needs a 75-gallon tank minimum; a single female needs a 125-gallon tank minimum (Austin's Turtle Page). A common rule of thumb is at least 10 US gallons of water per inch of adult shell length. Bigger is always better for these active swimmers — hatchlings can start in a 20-gallon long, but plan for the adult tank from day one.

72-76°F (22-24°C) for adults and sub-adults; hatchlings and small juveniles do better a bit warmer at 78-80°F (26-27°C). A submersible aquarium heater (guarded so the turtle can't crack or burn on it) holds it steady.

As deep as you can give them — map turtles are powerful, confident swimmers who thrive in deep, open water. Hatchlings start shallower at about 4-6 in with plenty of easy resting spots and structure to climb, then go progressively deeper as they grow. Always provide submerged rest ledges so they can pause without a hard swim to the surface.

Heavy filtration is essential — these are clean-water river turtles and they're messy eaters. Use a canister filter rated for at least 2x the tank's actual water volume (turtle keepers routinely over-filter). Strong flow also oxygenates the water, which map turtles appreciate. Do partial water changes weekly regardless of filter size.

A completely dry basking dock (floating platform, cork slab, or above-water ledge) they can climb fully out onto and drip-dry. Map turtles are "aggressive baskers", so make it easy to reach and stable. Basking-surface temperature ~95–100°F (35–38°C), up to ~110°F at the hottest point for large adults (per Austin's Turtle Page), always with a cool side to move to.

Lights and basking heat off at night is fine. Room temperature down to the mid-60s°F (around 18°C) is acceptable as long as the water stays in range; if the room gets cold, the water heater keeps the tank stable overnight.

Real UVB is non-negotiable. Use a linear T5 HO tube — Zoo Med ReptiSun T5 HO 5.0 or Arcadia Forest 6% — running the length of the basking end (about 50-75% of the tank length). Like the closely related slider (Ferguson Zone 3), aim for a UV Index of about 3.0-4.0 on the dry basking surface. Mount a 5.0/6% tube roughly 11-13 in (28-33 cm) above the platform (a 10.0/12% tube goes higher, 17-21 in), never closer than 10 in, and never behind glass or fine mesh — glass blocks ~95% of UVB and mesh ~30%. Replace the tube every 12 months even if it still glows.

Bare bottom is easiest to keep clean and is perfectly fine. If you want a planted, natural look, use sand or river rock/gravel that's either too large to swallow or fine enough to pass — avoid the small-to-medium gravel a turtle could gulp and impact on.

Offer a cuttlebone or calcium block floating in the tank at all times — they'll gnaw it and it buffers the water. With proper UVB, extra vitamin-D3 dusting usually isn't needed; only supplement D3 if you cannot provide good UVB (which isn't recommended). Snails and other whole, shelled prey are also a natural calcium source.

Males stay small at about 4–6 in (10–15 cm) shell length; females are much larger at 7–10.75 in (18–27 cm). This big size gap matters — a female needs roughly double the tank of a male.

Commonly 20–30 years with good care — AnAge documents about 18 years in captivity and 20+ in the wild. A long commitment.

See a reptile or exotics vet if you notice: Swollen, puffy, or shut eyes, or a runny nose, whistling, or open-mouth breathing — possible respiratory infection or vitamin-A issue; see an exotics vet.; Soft, spongy, or pyramided shell, or a beak that won't stop growing — signs of poor calcium/UVB and metabolic bone disease.; White, red, pitted, foul-smelling, or flaking patches on the shell or skin — possible shell rot or fungal/bacterial infection.; Refusing food for more than a week or two once settled, sudden lethargy, or floating lopsided/unable to dive evenly — get it checked.; Basking constantly and never entering the water, or staying underwater and never basking — a behavior change worth a vet call once husbandry is ruled out..