Potentially Stressed Out Fish?

[mrbilbertson]

Hi all,
 
Need a little advice here as I cannot think of a solution.
I have been running my fish tank for over a year now with the last fish being introduced about 6 months ago.
 
In the last week, I have noticed that all my fish have become very jumpy and dart around my fish tank at the slightest movement in and around the tank.
 
My first instinct was to test the water, and everything came back absolutely fine. Next I done a 50% water change just in case the water had been poisoned or contaminated in and way and I added live bacteria so as not to take out too much goodness from the water, but still they all seemed to be very jumpy. 
 
All the fish are feeding well whenever I feed them and act normal whenever they are being fed, but once the foods gone, they go back to their jumpy selves.
 
I’m now completely clueless as to what could be causing the fish to act like that and hopefully you guys and gals could help out cause I’m at a total loss,
 
i have a 110L tank with 1 krib, 2 keyhole cichlids, 3 corys, 6 ruby barbs, 6 phantom tetras and 2 rosy barbs.
Thanks in advance for any help
 
Alfie
 
 

 

[betta fish]

I'm not sure but a couple of things spring to mind, has the tank location changed? is there more light or do you approach from a different angle near a window? I'm thinking they may be able to see your shadow and react, other than that has any decorations/plants been removed? is there plenty of cover in the tank? if not I would go about planting it up lots to make the fish feel more safe