Cory Behavior

Hi, so I have just added 4 Bronze Cory cats to my tank. They have had a hard time due to their size( they are about 1.5cm 2cm at most) and in my tank of silver dollars they have been chased a bit and one was in my dollars mouth but we got it out. I bought them on the advice of LFS told they'd be fine as dollars are friendly with small mouths.
Now one is always at the top of he water, no injuries visible, and water perimeters all good and stable my test kit shows all test clear or smallest measurement possible  (ammonia,nitrites& nitrates) PH is 6 and stable.

I have the option of putting him in my other tank with Danios but as that's cycling I'd rather not as think that would be more stressful and I can't find the other 3 Corys although I can see 1 of them I feel 2 might have been eaten.Feeling hopeless as I like many on here love them little guys and have been really looking forward to adding them to my tank. Thanks in advance 
 

The dollars are leaving them alone at the mo,I have upped the feeding to keep them occupied.
My second tank is really too small for the corys as its only a 1.5ft cube typed with a handful of danios, grass, moss, and java fern I am trying my hand at aquascaping this is my first attempt. Parameters are all still good little nitrites but no ammonia or nitrates.