The sterbai were super shy for about 2 1/2 years but when enough floating stuff grew to block a lot of the light that calmed them down; they really do better if a part of the aquarium is well shaded. Odd thing is they will now spend a lot of time on the 'sunny' side rather than hang out in the shade - i guess the knowing there is a darker area makes them feel safer.
How big are your sterbai now? Could I see pics next to a ruler to help me get a better sense of what I would be in for if I buy some?