Hmm, What could i have in my tank?

i have a 22 litre (freshwater) aquarium with a 2w air pump and a 3.5 w enternal filter(elite stingray 5).currently in the tank are 3 zebra danios 1 fantale 5 malaysian trupmet snails and an apple snail.the temp is 19 degrees celcius.could i have any type of shrimp or crab in the tank?