I got an American flag fish about a month ago to help clear some algae but I saw her chasing some fish around today and spotted a split on a tail that I am not sure was there before. Also I bought a male sunburst wag platy yesterday and today his tail looks chewed on. To tell you the truth when I got him his tail could have alreday been like this and I did not pay attention because I also got alot of tetras the same day. my gourami has also chased a fish or two but I have never seen visible damage. So is this something that I should be worried about because I have never seen damage before except for today. Also I bought a second female to give the first one friendly.

As far as i am aware both male gourami's (depending on the type) and male flag fish can be territorial, so it would be good to find out the genders of the fish.

The flags are female for the territorail reason the gourami I am not sure but I have no problem with him because he has never really caused problems.

Firstly are you sure you have a female (the sexes are quite distinct) Males are more colourful. Females are stocky, smaller and somewhat drab and will have a dark spot on the dorsal fin.

Jordanella floridae (American Flagfish) can be quite territoral at times especially when breeding or a male kept on his own. I have bred these on may occasions and find them a beautiful little fish but as I said earlier some rogue males can become quite boisterous.

Never kept a lone female with community fish, so maybe female develop the same trait. Keep observing and you will find the true culprit.
Regards
BigC