It really depends on him. Since he is a half giant, it makes it more iffy. I have a giant in a 10 gallon currently, and I know he makes a lot of waste!
Is the tank cycled? Do you have a testing kit? If not I recommend API Master Kit which is 100% better than the strips.
Shrimp tend to be eaten, snails tend to be messy... A 10 gallon is really hard to find compatible fish for. Tetras can be nippy, or he may attack them. Female guppies (less colorful) may work, but again it really depends on his temperament.
If you do buy fish for the tank, find he is very aggressive or they are aggressive, do you have a back up plan?