The grey things with white bellies could be otocinclus catfish. They look like it from your before picture. Are they still in there? When you got the bucket was everyone living like that for a while? If so, then I agree, leave it alone, you’ve only improved their situation.
It they were dumped in there to give to you, I’d consider maybe an airstone to increase oxygenation. Otos and shrimp will eat biofilm and algae. So long as you continue to feed them and generate biofilm as extra food, should be OK. If the otos start getting paler maybe introduce algae wafers slowly?
The assassin may have buried himself to lurk for snails to hunt. If you don’t have any, which it doesn’t seem like you do, he could be bumming. Any in your other aquariums?
lordizzlel 
Seems fine to me, they dont need much care. In fact they do better if neglected
The grey things with white bellies could be otocinclus catfish. They look like it from your before picture. Are they still in there? When you got the bucket was everyone living like that for a while? If so, then I agree, leave it alone, you’ve only improved their situation.
It they were dumped in there to give to you, I’d consider maybe an airstone to increase oxygenation. Otos and shrimp will eat biofilm and algae. So long as you continue to feed them and generate biofilm as extra food, should be OK. If the otos start getting paler maybe introduce algae wafers slowly?
The assassin may have buried himself to lurk for snails to hunt. If you don’t have any, which it doesn’t seem like you do, he could be bumming. Any in your other aquariums?
[This right here](https://imgur.com/a/TCwLgnd) is how they came to me