Efforts to trace close contacts are underway with 10 identified advised to self-isolate.
Pupils who have not been identified as close contacts of the positive case have been told they are to attend school as normal unless advised differently.
In a letter to parents, headteacher Neil Hendry has said: “I realise that this news may be unsettling.
“I want to reassure parents and carers that there is no evidence of transmission of Covid-19 within Lochside Academy and that the school has very good control measures in place which were commended by the health protection team.
“The strength of the control measures in place has enabled the health protection team to advise that the school [can] remain open.”
Another Covid-19 case confirmed at Aberdeen secondary school