It sounds like the aquarium was probably overstocked for a newly cycled tank. I would suggest that next time you add fewer fish and not all at the same time.
I think that might be pushing it with the rams, kribs, apistos, and angels. I’m not saying it couldn’t work but I think you’d be asking for trouble with that many different species of cichlids.
I would suggest some frozen food if some sort. You can buy it at almost any pet store and it will keep for a pretty long time in the freezer. You could also buy black worms from an aquarium store or online.
I agree with @bettta999 I think a black background would look great on that aquarium. You can buy them precut at most pet stores and tape them to the back of the aquarium.
I always use them in my 10 gal shrimp and snail tank and it works well. I put one small one in and then wait until it completely dissolves before adding another one.
I completely agree with @813aquatics it looks great and I think they would love it. If you want to breed them you might need to buy a dedicated pleco cave.
They come in many different color variants including red, albino, chocolate, green dragon, white, and mixes of those colors. They grow 4-5 inches and love green beans!