mangrove reef

So I have my little mangrove, and have had it for about a month, not the leafs start to brown, and don’t know what I’m doing wrong, a had a couple rots braking of in transit but I did as recommended and glued them with Reef safe super glue, what can I do to save my tree? Should I pot it instead...

I’ve been wanting to get a mangrove tree for my tank just to have one. I think there so pretty. Here’s a picture of my tank. I have egg crate on top. I don’t want it in my sump. Any ideas where I can put one and also advice and suggestions how to grow one?