Bottom Walkers
Author: Chris Robinson and Paul Eversfield
There is a group of smaller turtles from the central and southern states of the USA, with cousins that extend down through what we call Central America and South America, the Kinosternidae. These are more suitable for the private hobbyist, while retaining some of the "charm" of their monster cousins, the Snapping turtles. Most of these Mud and Musk turtles are similar in character to the larger Snapping Turtle group, but because of their size are better suited to the home aquarium. This group comprises some Forty one species, including the currently recognized sub- species. They take their name from their hinged plastron. With a range of habitat, throughout central and North America, they extend into the South America. All, may be characterized as "bottom walkers" rather than "swimmers", and as such need (or at least do best in) shallower water than, say, sliders.
There are several that are commonly available within the pet trade:
The Common musk turtle (Sternotherus odoratum). These are usually sold as hatchlings less than an inch in length. At this size they are relatively delicate, though they are feisty, and will try to bite the hand that feeds them. They rarely exceed 5", when adult.

Similar in size is the Razorback Musk (Sternotherus carinatus):

These North American representatives are all temperate turtles that require little heating in indoor tanks and will survive outdoors in this country in ponds when adult. However when they are small all of these turtles need to be able to easily access the surface to breathe. If the water is too deep the can exhaust themselves trying to reach the surface and drown. There are several ways to overcome this problem. You can slope the floor of the tank so that one end is deeper than the other. You can put in slabs at different levels or simply keep the water shallow, making it deeper as they get older.
Filtration is very important, as with all turtles. However these species don't seem to appreciate a heavy current such is caused by big external filters. This is especially true of hatchlings, where the depth of water anyway makes internal filtration almost inevitable.
They leave the water to bask, but this varies with individuals. Many only seem to leave the water at night to rummage around their enclosure. Others will bask with access to natural sun light or a basking light (UV emitting).
They are, in nature, primarily molluscivores, but will eat some vegetation, and pond weed or duckweed should be available for them at all times. The advantage of aquatic plants is that they provide essential cover, which is very important to these crepuscular Turtles, and of course keeps a natural balance in the water of the aquarium. They love live food such as worms and crickets (though size can be an issue with the very small babies) and a good varied diet is essential. Dried foods such as Reptomin are ideal, though there are several different brands on the market each with a slightly different composition. It is usually advisable to mix them.
They are generally too slow to catch active fish, and something like White Cloud Mountain Minnows are a good choice to put in with them. Apart from the added visual interest they clean up after the turtles and act as "canaries", an early indicator of water quality. They are also tolerant of a wide range of water temperatures.
One of the semi-tropical species that I have regularly bred is the Red Cheeked Mud Turtle (Kinosternon scorpioides cruentatum). This occurs in Central America, Mexico, and neighbouring countries such as Honduras:

The turtle is relatively small with adults measuring 10/12cm. Males are distinctive in that as they mature, their tail elongates with a sharp spur at the tip. A common name for these and some of their close cousins is Scorpion Mud Turtle. The Red Cheeked Mud turtle has reddish blush around the head, which in breeding condition is very pronounced in the male.
These highly aquatic turtles live in slow moving rivers and ponds and tend to be very crepuscular, rarely basking above water at all. Their diet is made up of crustaceans and molluscs, but they will also take fish and carrion.
I have maintained a group of these animals for a number of years. My adults are one male and two females, which are kept in an aquarium, 112cm x 46cm x 31cm. The water is maintained at 26 degrees centigrade, and is filtered by an external canister filter. The aquarium has a substrate of large granite pebbles (cobbles). They share this environment with a shoal of Tetra and Neon swords. The fish interact well and are not predated if the animals are fed regularly (daily). Feeding for the most part is high quality Cichlid pellet, and shellfish. Occasionally, worms, snails and other live insect food are also offered.
Mating occurs several times throughout the year and is usually initiated following a significant water change. I have found with many tropical species of Turtle a 50% or greater water change stimulates courtship and mating. Perhaps the sudden change in temperature mirrors the onset of a "wet season". In any case, following a successful coupling after three to four weeks the females seek to nest and will leave the water to lay their ellipsoid hard shelled eggs. They will lay between two and four eggs in a clutch, which are incubated at 29-30 degrees centigrade. The eggs take 69-75 days to hatch.
I have kept Turtles from this group for over forty years. Their pugnacious temperament and active foraging habit in the aquarium is totally fascinating. Indeed, the group of Red Cheeked mud turtles shared my office and regularly held visitors' attention for ages. They were never sure what the "living pebbles" were going to do next.