I already posted a message to you on the box turtle forum, but I just wanted to add, that a 4 yr. old child is not really capable of caring for any type of pet, and there are very few pets that are suitable for a child that young. If you want to take the responsibility of caring for the animal and supervising the child carefully, then a leopard gecko "might" be OK, but personally I wouldn't get one. Teach your child the proper way to approach and handle all kinds of animals, take him/her to shows, zoos, etc., and observe how the animals react and vice versa. Then think about getting a pet. Around age 8 is usually a great age for reptile ownership, and they can really be involved in care.
If you want to get a pet for yourself, great, but your post didn't sound that way. Please don't buy a turtle or tortoise and let it be a throwaway.
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Sohni
Northern California
0.1 Baja de L.A. Rosy Boa
0.1 Okeetee Corn Snake
1.1 Rubber Boas
1.0 Leopard Gecko
0.0.1 Hermann's Tortoise
0.0.1 Marginated Tortoise
plus my kids' herps:
0.1 California King Snake
1.0 Mexican Rosy Boa
0.1 Leopard Gecko