resetting up tank

so i have a tank that hasn't had fish or been running for sometime now. water tested fine aside from the ph its slightly low. would it be a bad to introduce a fish?

 

That depends on how many you add at once. Your biological filter is almost non-existent since it has been fallow for sometime. Also if the water has had no circulation then you will most likely have anaerobic bacteria in your substrate and that will be bad for your new fish and any bacteria being introduced.

I would thoroughly clean the tank, filter and substrate and start over as if it was a new tank.