Paraplegic Fish/ac As Substrate?

[Howard0]

Is it possible for fish to become paraplegic? I was changing some of my gravel today, caught my molly in a net and put it into a holding container. When I dropped it in it was in a C shape. Then it started swimming around. Now that it's back in my tank it's roaming but only using it's front find and never its tail.
 
On a side note. Is it possible to use Activated Carbon as a substrate? I know it's powdery so you'd have to b careful not to disturb it. (Do rock forms exist?)

 

[ag-au]

The fish could be injured. As for the activated carbon as a substrate I'm finding conflicting views on the webs. Some people say it will absorb toxins and NOT release, others say it will absorb toxins and then release them all at once. A conclusive bit of info is that it will sink but any flow will kick it about. Also, i'm reading that you would have to rinse it very well as a sizeable amount will stain the water. IMO, black sand would be better than AC. BUT I have never used this. Give it a shot and let me know?