If nitrite really is that high, you would see signs of it in the fish. They would be respirating very hard, likely near the surface, possibly even gasping. Gills would be brownish/red [nitrite affects the blood and it becomes brownish], gill covers likely flared open. Fish would be lethargic, then death follows very quickly. If any of these signs are present, do a major water change [test the tap water for nitrite, it can happen, though not likely].
If the fish do not show any of these signs, and appear normal, I would just leave things alone and discount the test completely.
Make sure you do not add more drops than what the test instructs; when the bottle is upside down, it can be tricky to keep the drops even.
Have you tested for nitrite previously, and was it zero then, with this same bottle of regent?
Byron.