A type of Aequidens I'd say, diadema or one of the similar species, with diadema, metae, and (somewhat less so) sp. jenaro herrera being most common in the US. Care is similar between them and temperament is variable, depending on gender, gender mix, individuals, tankmates, etc. Not always easy to Id-- several Aequidens species are similar, the same species from different locations can vary, and (from personal experience) individuals can look different depending on mood, tankmates, or which tank you put them in. I've had people quite confidently get it wrong on ones I had with known provenance.
Kevin@TUIC
may be able to tell you species.