I don't have any experience with this personally, but their is sufficient anecdotal evidence on these forums that your common pleco could become a problem for your Delhezi.
You don't know if they bury in the sand, or what you should feed them. This tells me that you bought the fish with little thought other than you like how they look. I'm not saying I've never been guilty of this but now that you have the fish give yourself an education on their care. Read this thread and watch the video:
https://www.monsterfishkeepers.com/forums/threads/all-bichir-polypterus-species-updated.684410/
We're all happy to help, especially in the Polypterus section, but most of the information you'll ever need and 100% of the information you need on basic care are all in this forum already.
You don't know if they bury in the sand, or what you should feed them. This tells me that you bought the fish with little thought other than you like how they look. I'm not saying I've never been guilty of this but now that you have the fish give yourself an education on their care. Read this thread and watch the video:
https://www.monsterfishkeepers.com/forums/threads/all-bichir-polypterus-species-updated.684410/
We're all happy to help, especially in the Polypterus section, but most of the information you'll ever need and 100% of the information you need on basic care are all in this forum already.
