The loach needs buddies, they are very social fish. Unfortunately you need a very large tank (120g+) for a group of Clown Loaches. If you like the look of the loach and it's personality, there are smaller varieties you could keep instead. Dwarf Chain Loaches are a good option.
Otherwise, you have a lot of options for colorful schoolers that get along with neons. Bear in mind that they like things on the cooler end of the tropical spectrum, so stick to ones that like similar temps like White Cloud Minnows, Rosy Barbs, Black Skirt Tetras, Harlequin Rasboras, etc.
For non-schoolers, a dwarf gourami would look nice. Stick to one male though, as they don't tolerate other males very well. Smaller Killifish may work as well, such as the Gardneri, Lyre-tails, etc. Avoid the large mouthed varieties as they'll try to eat the Neons when they're full grown.