I had them for more then a month now. Then in the last couple of days my plants leaves started to turn black plus the stem don't know what happening.

Could you please tell more about your watering regime, for help the xp members to debunk the problem?

(For me, it looks overwatering with some bad soil choice, but me is... just me... )

Felidae wrote: (For me, it looks overwatering with some bad soil choice, but me is... just me... )

But you may be right.
The plant is sitting in a pool of water, and the vase has no feet. Sure recipe for overwatering and fungal infections.

Clicio wrote:

Felidae wrote: (For me, it looks overwatering with some bad soil choice, but me is... just me... )

But you may be right.
The plant is sitting in a pool of water, and the vase has no feet. Sure recipe for overwatering and fungal infections.

Yup, here looks like have a good chance that I’m right. I didn’t thought about the current water level on the tray, cause it could be fresh watering before discarding the excess water, but more on the way how they declined.

I usually water the umbrella tree every week to every week and a half right now it's in potting soil basic potting soil with some gravel until my Akadama soil plus my black lava rocks arrive. This are some pics of what they looked like before all of this started happening

You probably let it dry out too much. Then roots died, and when you watered again they started to rot. Or, as Felidea indicated, you have kept them too wet overly long. But hearing how you care for it, I would go for the first.

I do not see this recovering.