Can a Musk Turtle Live in a 20-Gallon Tank?

By Hektor Jorgo Published November 10, 2026 Updated June 14, 2026 5 min read

A small common musk turtle resting on the bottom of a shallow aquarium near rockwork

Quick Facts

Species in Question: Most often the common musk turtle (Sternotherus odoratus), one of the smallest commonly kept aquatic turtles
Adult Size: Roughly 3-4.5 inches (7.5-11 cm) shell length
20-Gallon Verdict: Workable for a single adult musk turtle long, but tight — 30-40 gallons gives meaningfully more room
Water Depth Preference: Shallower relative to body size than many turtles — musk turtles are weak swimmers that prefer to walk the bottom
Basking Needs: Still required despite musk turtles basking less than sliders — a dry, accessible platform with heat and UVB
Filtration: A tank this size needs filtration rated well above its actual volume given turtle waste output
Other Species Caution: Larger species (sliders, painted turtles, map turtles) outgrow a 20-gallon almost immediately
Growth Consideration: Musk turtles grow slowly, but 20 gallons is closer to a minimum than a comfortable long-term size

Tank size questions for pet turtles almost always come back with the same answer — "bigger than you think" — but musk turtles are one of the rare exceptions where a 20-gallon tank is actually worth a real conversation, rather than a non-starter.

Short Answer

A 20-gallon long tank is a workable minimum for a single adult common musk turtle (Sternotherus odoratus), one of the smallest commonly kept aquatic turtle species at roughly 3-4.5 inches of shell length. It's not generously spacious — most care guides suggest 30-40 gallons as a more comfortable long-term target — but it's genuinely in a different category from species like red-eared sliders, which outgrow a 20-gallon almost immediately. Musk turtles' small size and bottom-walking behavior (rather than active open-water swimming) are what make this size range realistic at all. Basking, filtration, and water depth still need to be planned carefully given the limited footprint.

Why Musk Turtles Are Different

The common musk turtle, sometimes called a "stinkpot" (a reference to a musky odor it can release when handled, not its tank), is among the smallest aquatic turtles regularly kept as pets. A couple of traits make it unusually well-suited to a smaller tank compared to most other species:

Small adult size. At 3-4.5 inches of shell length, a musk turtle is roughly a third to half the size of a mature red-eared slider. Tank size requirements scale with body size, so this matters more than almost anything else.
Poor swimmers that walk the bottom. Unlike sliders and painted turtles, which are active swimmers that cover open water, musk turtles spend much of their time walking along the substrate in shallow, slow-moving, or still water in the wild. This means a tank doesn't need a large open swimming column to feel appropriately sized for a musk turtle the way it would for a more aquatic species.
Shallower water tolerance. Water depth can be kept more modest relative to the turtle's size — enough for the turtle to be fully submerged and to surface easily for air, without needing the deep water column an active swimmer would use.

These traits don't make a musk turtle a "no-tank-needed" pet, but they do shift the math meaningfully compared to almost every other commonly kept species.

Tank Size: 20 Gallons vs. What's Actually Recommended

A 20-gallon long tank (the "long" orientation matters — it provides more floor space than a standard 20-gallon high) provides roughly 30 inches by 12 inches of footprint. For a single adult musk turtle at 3-4.5 inches, that's enough room to walk, turn around, and access a basking spot without feeling severely cramped — which is genuinely not true for most other turtle species at this tank size.

That said, 30-40 gallons is the more commonly recommended target if your space allows it, for a few practical reasons:

More room for a filter, heater, and basking platform without each one eating into the turtle's usable space
More flexibility for aquascaping (rocks, driftwood, plants) that musk turtles use for cover — they're a somewhat shy species that appreciates places to retreat
A bit more buffer for water quality, since a larger volume dilutes waste output more than a smaller one

Think of 20 gallons as "this can work, and is much more realistic than for other species" rather than "this is the ideal target."

Basking, Filtration & Other Setup Essentials in a Small Tank

Regardless of overall tank size, a few things aren't optional:

Basking area with heat and UVB. Musk turtles bask less often and less dramatically than sliders, but they still need access to a dry, warm spot with UVB lighting for proper shell and bone health. In a 20-gallon tank, plan this early — a corner platform or floating dock tends to be more space-efficient than a large ramp.
Filtration sized for turtle waste, not just tank volume. Turtles produce substantial waste relative to their size, and a 20-gallon tank's smaller water volume means that waste is more concentrated. A filter rated for a notably larger tank volume than 20 gallons is a common and reasonable recommendation.
Hiding spots and structure. Musk turtles are a bit more reclusive than sliders and appreciate rockwork, driftwood, or dense plants (real or artificial) to retreat into — this matters for behavior and stress levels, separate from the raw space question. If you're also thinking through what's safe to add to the tank as decor, our guides on decorations in a turtle tank and putting seashells in a turtle tank cover what works well in a space-limited setup.

What If You Have a Different Turtle Species?

This is the important caveat: almost everything above is specific to musk turtles (and similarly small species like mud turtles). If you have a red-eared slider, painted turtle, map turtle, or cooter, a 20-gallon tank is realistically only appropriate for a hatchling, and only for a relatively short time before an upgrade is needed — these species commonly reach 6-12+ inches and need 75-125+ gallons as adults. Our broader guide on whether a turtle fits in a 30-gallon tank covers the general "10 gallons per inch of shell" rule of thumb and walks through which species can realistically stay in smaller tanks long-term versus which ones need an upgrade plan from day one.

Quick Reference

A 20-gallon long tank is a workable minimum for one adult common musk turtle (3-4.5 in. shell length)
30-40 gallons is the more commonly recommended comfortable target if space allows
Musk turtles are weak swimmers that walk the substrate — shallower water and less open swimming space are acceptable
Basking with heat and UVB is still required, even in a small tank — plan the platform early
Filtration should be rated above the tank's actual volume given turtle waste output
Almost all other common pet turtle species (sliders, painted turtles, map turtles) outgrow a 20-gallon quickly

Frequently Asked Questions

Can a musk turtle really live its whole life in a 20-gallon tank?

It's closer to viable than for almost any other commonly kept pet turtle, but '20 gallons long' is more of a workable minimum than a generously comfortable long-term size. Adult common musk turtles (Sternotherus odoratus) typically reach only 3-4.5 inches of shell length, which is genuinely small for an aquatic turtle — for comparison, a red-eared slider can reach 8-12 inches and needs a tank many times larger. A 20-gallon long tank gives a single adult musk turtle enough floor space to walk around, turn, and access a basking area, which is the core requirement. That said, most musk turtle care guides suggest 30-40 gallons as a more comfortable target if you have the space, mainly because it gives more room for aquascaping, filtration equipment, and a less cramped basking setup without crowding the swimming area.

What makes musk turtles different from other small pet turtles in terms of tank size?

Two things: their small adult size, and their behavior in the water. Musk turtles are sometimes called 'stinkpot' turtles, and they're notably poor swimmers compared to species like sliders or painted turtles — in the wild, they spend much of their time walking along the bottom of slow-moving or still water rather than swimming through open water. This translates directly to tank setup: musk turtles do well with shallower water relative to their size than a slider would need, since they're not relying on open water column space to swim laps. A 20-gallon tank's modest footprint is less of a constraint for an animal that's mostly walking the substrate than it would be for an active swimmer that wants to cover distance in open water.

Do musk turtles need a basking area like other turtles?

Yes — basking is still a requirement, even though musk turtles bask less frequently and less dramatically than species like red-eared sliders. A dry, easily accessible platform with a basking light (for heat) and UVB lighting (for proper shell and bone development via vitamin D synthesis) needs to be part of the setup regardless of tank size. In a 20-gallon tank, this means planning the basking area early, since floor space is at a premium — a corner platform or a floating basking dock tends to use space more efficiently than a large ramp that eats into swimming area. Skipping or skimping on basking isn't a way to 'save space' that's safe to make — it's one of the few genuinely non-negotiable elements of turtle husbandry regardless of tank size.

What if I have a different turtle species, not a musk turtle?

Then a 20-gallon tank is very likely too small, even for a juvenile, and almost certainly too small for an adult. Common species like red-eared sliders, painted turtles, map turtles, and cooters all grow to 6-12+ inches and need substantially more space — often 75-125+ gallons for a single adult. Our broader guide on whether a 30-gallon tank works for a turtle covers the general sizing rule of thumb (roughly 10 gallons per inch of adult shell length) and which species realistically fit which tank sizes — musk and mud turtles are very much the exception rather than the rule when it comes to small-tank-friendly turtles.

Sources & Further Reading

About the Author: Hektor Jorgo

Co-Founder & Marine Biologist

Hektor is a co-founder of Sea Life Planet and has kept reef and freshwater aquariums for over 15 years. He holds a background in marine biology and focuses on species care accuracy, water chemistry, and tank husbandry.