How old are your fish? As a rule of thumb, Oscars normally become sexually mature from about one year onwards. From my experience, they start laying eggs at around 14 or 15 months old. By this time, they are anywhere between eight and 10 inches long. The behaviour that you describe certainly resembles the sort of behaviour that a breeding pair would carry out but having said that, I have noticed this type of behaviour many months before eggs ever came along so I shouldn't hold your breath for too long just at the moment