Over this past spring break, I made the somewhat unadvisable decision of buying three baby turtles. Oh yes. Not one turtle, not two turtles, but three baby turtles. Luckily, two of them are for my siblings, so I'm only taking care of one now. A few days after buying the turtles, I came to my senses and realized that I needed to do some research and make sure that I didn't accidentally kill the poor hatchings. I've done a lot of reading since then, and I can fairly confidently say that I officially know all the basics to turtle care. All of these recommendations are based off of sliders, which are the type that I have, so make sure to do your own research before applying them to any other breed.
Slider turtles are omnivorous overall, but their diets change throughout their lifetimes. Baby sliders are more carnivorous, but older ones can eat almost strictly vegetation. It's pretty easy to feed babies pre-packaged turtle pellets that you can find at pretty much any pet store (or Walmart), and they contain enough protein to keep them going in their early days. Just break up a few pellets each day and drop them into the tank.
Many types of turtles can only swallow when completely submerged (the water makes swallowing easier), so they can only be fed while in their tanks. Just make sure that you don't feed them more than they can eat in a few minutes, as overeating is just as bad for them as it is for us. I basically just drop the pieces in one by one until my turtle, Pompano, stops immediately biting them.
This is a biggie. Turtles are easy pets, but you do need to keep them in the right environment. First, they need to be in a tank filled with water, because aquatic turtles need to be able to fully submerge themselves. Multiple baby turtles can live together in a 10-20 gallon tank, but most adults need their own tank of at least 40 gallons. Although aquatic turtles need to be able to swim, they are not fish, nor do they have gills, so they also need to be able to come to the top of the water to breathe or they will drown. This means that they need both water for swimming and a place where they can get out of the water (aka land) to breathe and bask.
Basking is another important part of the aquatic turtle's life; without a place to bask (which requires land, a heat lamp and a UVB lamp), their shells will get soft and they will have lots of health problems. An easy way to have land for the turtles (while conserving as much tank space for water as possible) is to get a ramp that can attach to the top of the tank. Just make sure to enclose their land space so they don't escape! The UVB lamp is especially important because without it, turtles develop weak bones.
Turtles are also cold-blooded creatures, so it is extremely important to keep both their water and their basking areas warm. The water should be between 70-80 degrees Fahrenheit (on the higher end for babies, on the lower end for older turtles), and the basking area should be around 90. The basking area can be kept warm with the heat lamp (which I've already mentioned), and the water can easily be heated using an aquarium heater. Just make sure to test the heater out for a while before putting the turtles in to make sure that it doesn't short out and zap the poor babies.
Lifespan and size
This is the thing I probably thought about least while buying my turtles. Remember in "Finding Nemo" when Marlin asked Crush how old he was? Normal aquatic turtles don't live as long as sea turtles (didn't Crush--he was 150 and still young?), they can live decades if properly cared for! As one of my friends aptly pointed out, I will probably have children by the time Pompano dies.
Also, turtles do not stay small forever, and a small tank will not keep them from growing (unlike goldfish). Certain types of turtles grow bigger than others, so take this into account when choosing yours. Pompano is a slider, so he could grow to be anywhere between 5 and 12 inches long, depending on his gender (which is nearly impossible to determine until adulthood). Obviously, since I'm going to be living in small Chicago apartments for the foreseeable future, I'm hoping he is actually a he, because females get much bigger. Painted turtles, on the other hand, rarely get above 5 inches, so may be better for owners with more size restrictions.
Some other random things about turtle ownership:
Know that it is illegal to buy or sell turtles with shells less than four inches long (oops). Also, certain states have different laws regarding turtles as pets, so make sure to read up on these before you make your purchase.
Know that aquatic turtles naturally have strong fight instincts and are really shy, especially the babies. Pompano tends to sprint for his underwater cave every time I walk into the room. Make sure you give your turtles places to hide in their new homes!
Turtles also seem to have personalities, just like us. I took care of all three turtles until my siblings came back from their spring break last week, so I had the chance to experience this first-hand. My brother's turtle, Jeffrey, is extremely aggressive and high-energy, and is always the first to try to escape and go for all the food. I frequently had to remove him from the tank after feeding him so I could get food to the other two. On the other hand, Pompano is (probably) the youngest, and therefore the shyest. He spends most of his time in hiding, and rarely comes out for food unless I sit perfectly still for minutes at a time. My sister's turtle, Yertle, has a personality somewhere between the other two (which is weirdly extremely representative of our personalities as well).
Turtles can get sick. One of their most common sicknesses is basically the flu. This can be caused by being exposed to cold temperatures for too long, and symptoms include a lack of eating and swimming with one part of their bodies higher than the other (because they have air in their lungs that affect buoyancy). Turtles with the flu generally need antibiotics from a vet that specializes in reptiles.
Finally, turtles sleep underwater. They know when they need to come up for air, and they will as long as it's available. I spent a few days thinking Pompano had the flu, and was really concerned when he just hung out on the bottom of the tank for hours. Turns out he was fine, and I had nothing to worry about!
Enjoy your new friends!