The Synodontis Angelicus are one of the more aggressive catfish. You may be better off with Synodontis Multipunctatus three or more or Synodonts Petricola three or more or the Lake Malawi Synodontis Njasse.
In my aquarium i keep four Multipunctatus, a Synodontis Decorus, a Synodontis Shoutedeni, and I added a small Synodontis Angelicus six months ago. There are no issues yet. In my 180 i keep haps and peacocks with the catfish. I have multiple tanks and know that I may have to move the Angelicus at some point. They are really cool looking.
Good luck
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