gasping fish

Hi i am new at keeping fish and hope someone can help. I have had my fush 1 week and noticed they have been gasping over 48 hours. I cannot seem to lower the nitrate and nitrite levels. I have a 40 litre tank with 2 mollies, 2 swordtails, 1 betta and 2 african dwarf frogs. They get fed on 1 cube of frozen bloodworm twice a day and i have performed a 50% water change which has had no effecton the fish. Nitrite is reading 10ppm and nitrate is reading 200ppm. I am using the api 5 in 1 test strips. Can someone please help me before i start losing my fish??
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