six new cory cats - behavior and feeding questions

On the light and the fish response...this is likely due to there not being overhead lighting previously, now there is. The white sand makes this even brighter because it reflects light which is un-natural for the fish. Try unscrewing one bulb so only one is on and see if that helps. Once they are used to it, both may be less stressful. Floating plants will help--Water Sprite is ideal; the bit in the store may not look like much but this is common and it may recover, though not seeing it myself, hard to say. But I have brought home some pretty pathetic plants that do rebound in good light and conditions.

Stay with the shrimp pellets if they are eating those, and don't overfeed. Some of the small snails (Malaysian Livebearing, pond, bladder) would help as they will deal with uneaten food before it becomes a problem. Fish sometimes need time to "learn" about different food, and these being new in this tank are still under stress.

Ok, sorry for the big pictures, but I thought the detail was important. So this stuff that I thought was food floating all over the tank this morning, is it really food? You can see it sitting on the branch things and on the moss ball and on the silk leaves, and what is that squirmy thing on the bottom? Is that poop? I've never had sand before, so everything just disappeared into the gravel. But I was going to very gently stir up the water a little bit in hopes that the filter would get it out, and I went to brush it off the spider wood and the whole branch is super slimy! It's from an aquarium store and I soaked it in a bucket for like 4ish hours and rubbed it with fresh water before I put it in. Is there slime coming from the wood? Or is it from something else and just sticking to the wood? I checked the water with a test strip. Everything looks normal, nitrates are about 30ppm, and I was going to do another 25% water chance to get rid of at least some of the gunk anyhow, even though I just did one like 3? Days ago

And yes, I'm still working on changing the background to black paper instead of the foil, but I haven't got to the craft store yet, probably tomorrow. And this picture is with the operating room level lights on, no camera filter, I just read this and will unscrew one of the bulbs, but I have not been leaving it on for long because I couldn't even live with lights like this

For a reference, this is what the lighting level normally is, although it is a bit more brown than yesterday from the dark wood. And again, I do plan to get more wood for hiding spaces, but I'm trying to avoid having my husband freak out over me spending $50 on wood (the pieces I thought looked nice were about that much) the ones in there were $8 each, is that about standard for aquarium wood?