it's best to keep them in groups aswell, you may see more of it then.
I have since found this out since getting my lonely spotted dora at 2-3 inches and will be taking home 2-3 striped doras from the fish order this week. I think they will come in the same size as yours.
My tank has 2 large bits of wood in, bog wood and mopani which has lots of interjoining litle holes, currently the botia stratia and clown loach love playing in them!!