Am I ok to put another fish in the tank

[Fisherman45]

Ok I have a 70 gallon tank and 2 air stones. I have a 7”. Sevrum,5” pearl cichlid,and a 3” jack Dempsey,and 7”pleco.am I safe to add another fish cause in the past they would die from disease or lack of oxygen now I have 2 air stones am i safe to add another fish?

 

[Amazonian]

Do you only have air stones? Or what other filtration do you have?