I'd be afraid it would be stressful for the neons, actually. Five is the minimum number for a school. I got 10 for my 54 gallon tank, and they were fairly shy still until I added 10 rummynose tetras. The 2 kinds of tetras now school together, and the neons are not timid at all anymore. In fact, they are the second fish (behind the piggtastic harlequin rasboras) to swarm my fingers during feeding time.