My espeis were skittish when I first got them - they hid away in the back corner. The thing that made them less skittish was the floating plants. I got some water sprite and they stayed under that; as the water sprite covered more and more of the surface, they cam further into the tank but still under the plant. I have since swapped the water sprite for frogbit and the roots of that almost reach the bottom of the tank creating a sort of forest of roots. The espeis seem quite happy swimming through the roots.
As your salvinia grows, and the fish become more used to your tank and its surroundings, they should be less skittish.
Now that you have shrimps, just to warn you that should you ever buy more plants you need to make sure they are shrimp safe. Plants grown outside the EU have to be treated with snail killer, which also kills shrimps. Sites like ProShrimp, and Ebay sellers such as k2aqua guarantee their plants to be shrimp safe; and any plant grown 'in vitro' is also shrimp safe even if the seller doesn't say this.
