Mississippi Map Turtle — Fact Sheet

Graptemys kohnii · Mississippi Map Turtle

Full care guide and sources

📋 At a glance

🏠 Enclosure

One adult needs at least 120 cm tank length for an adult female; males are smaller but still need strong swimming space. Larger is always better, especially for females and strong swimmers. A bare small tank is not acceptable long term.

This river turtle benefits from long swimming runs, clean moving water, submerged resting shelves, and several secure basking exits. Current should create choice, not force nonstop exercise. Map turtles are alert and often dive abruptly when disturbed, so place the enclosure away from constant foot traffic and give visual barriers. A stable ramp and broad platform reduce repeated failed basking attempts.

The setup must include:

• deep enough water for normal swimming and turning
• an easy route to the surface
• a dry basking platform that supports the full body
• secure lids or high walls to prevent escape
• visual cover and resting points

Cohabitation is risky. Males may harass females, and turtles that appear peaceful can still bite, compete, or stress each other.

Quarantine a new map turtle in its own cycled system with dedicated nets and siphons. Record weight, appetite, feces, swimming symmetry, and basking frequency; an animal that never basks may be responding to disturbance, poor access, low surface temperature, or illness. Arrange reptile-veterinary examination and fecal testing for imported or uncertain-origin individuals before equipment is shared.

🪨 Substrate and furnishings

Use smooth rocks, driftwood, cork, sturdy aquatic plants, and resting ledges. Avoid sharp stones, unstable piles, tiny gravel that can be swallowed, and decorations that trap the turtle underwater.

Substrate can be bare-bottom, large river stones, or sand depending on the species and filtration plan. Every decoration must be easy to clean and impossible to collapse.

💡 Lighting

• Ferguson Zone 3; aim for UVI 3-4 at the animal’s back or shell height on the basking site. See the full care guide for the evidence and any uncertainty.
• Measure with a Solarmeter 6.5; provide a gradient to fully shaded retreats near zero UVI. Lamp percentage alone does not specify exposure.
• Photoperiod: 10-12 h; no bright night light.

🌡️ Temperature

• Basking surface: 32-35 °C

• Night air: 20-22 °C

• Water: 22-26 °C

• These are indoor active-season targets for healthy adults. Night means room air, not a target for cooling the water. Measure the dry platform with an infrared thermometer, air at shell height with a probe, and water with a separate immersed thermometer. Control and guard the water heater; the turtle must be able to leave the heated platform and dry its whole body.

• Hatchlings need warmer water, around 26-27 °C; the adult water range is not a hatchling target.

💧 Humidity and water

Aquatic turtles foul water quickly. Use oversized external filtration, regular partial water changes, and mechanical cleaning of trapped waste. Filter ratings for fish aquariums are usually too optimistic for turtles.

Ammonia and nitrite should remain at zero in an established system. Cloudy water, smell, skin irritation, and repeated eye problems often point to poor water quality rather than a need for medication.

Map turtles are particularly unforgiving of dirty, stagnant water. Use ample mechanical and biological media, test ammonia and nitrite after filter servicing, and preserve the biological colony by cleaning media in removed tank water rather than replacing everything at once. Diffuse part of the return to retain a calm resting zone, screen powerful intakes, and guard any heater against impact.

Humidity is usually managed by the water itself. The important point is to keep the basking platform genuinely dry and warm so the shell and skin can dry completely.

Clean drinking and swimming water are the same system for most aquatic turtles, so water quality is a husbandry requirement, not decoration.

🪳 Feeding

Feed a varied diet based on quality turtle pellets, aquatic insects, snails, mussel and shrimp items, occasional fish, and some aquatic vegetation. Juveniles usually need smaller, more frequent meals; adults should be fed more moderately to prevent obesity and water pollution.

Adult females are strongly adapted to larger molluscan prey, while smaller-headed males take relatively more insects and small snails. Match items to the turtle’s head size; do not give a small male oversized hard prey simply because it is suitable for a large female. A complete pellet can anchor the ration, supplemented with safely sourced snails, earthworms, aquatic insects, and some greens. Avoid wild prey from polluted water, dried shrimp as a staple, and plain fish or meat diets with poor calcium balance.

Calcium should be available through whole prey, cuttlebone, or appropriate supplementation. Do not use mammal meat, dog food, cat food, bread, dairy, or fatty processed foods.

🩺 Health — warning signs

Common problems include shell rot from a wet basking area, eye and skin irritation from dirty water, obesity from overfeeding, soft shell or poor growth from inadequate UVB/calcium, burns from unsafe heat lamps, and injuries from cohabitation.

Retained scutes are often associated with poor basking access, inadequate heat or UVB, fast growth, or water-quality problems; do not peel firmly attached scutes. Sudden listing, floating, nasal bubbles, wheezing, swollen eyes, or shell lesions require veterinary evaluation. Optional seasonal cooling is only for healthy, established adults under controlled conditions. Mature females need a secure, deep nesting box even when kept alone, and prolonged digging or straining can indicate dystocia.

Persistent swelling, floating problems, refusal to eat, wheezing, open-mouth breathing, bleeding, or shell lesions require an experienced reptile veterinarian.