I would not recommend getting anything labeled shark for your tank. Most of these get quite large, as has been mentioned. If you want something like them, you might consider pygmy corydoras, a group of 5.
A 10g tank is not appropriate for most common fish, thought it seems to be one of the most popular sizes for tanks. Ironic, isn't it? Other options for your 10g tank are as follows:
Option 1: A single betta with some snails and/or shrimp (betta might pick on/eat the inverts though).
Option 2: A single kribensis with snails.
Option 3: A group of pymgy corydoras (no more than 6 but must be at least 3).
Option 4: A group of 6-10 small schooling fish like neon tetras.
Option 5: A single ram (these can be difficult for beginner aquarists, though, as they are sensitive).
Option 6: A group of about 7 boraras urophthalmoides (exclamation point rasboras), a very small fish
Option 7: Least killifish (not sure you could have, experts?).
There are more, but I can't think of them off the top of my head right now.