Dwarf Gourami - Nipped

[lsouthgate27]

I have set up a tank in the last 6 months and have a few guppies, two red wagtail platys and two dwarf gourami's. Recently, one wagtail has been nipping at my gouramis. Mainly at their side fins and body not their tails. It is only one of the wagtails and I was wondering how I can prevent it and how much harm can be done in this situation?
Every other fish in the tank get along.

 

[Tokis-Phoenix]

Gourami's prefer peaceful planted tanks, ideally ones with lots of floating plants (doesn't matter if the plants are real or fake). You can't change the behavior of a fish so you may have to rehome the wagtail, but adding more planting to the tank will certainly protect the gourami's a lot more & reduce their stress levels. Injured fins can be susceptable to finrot, while the fish being stressed in general can compromise its immune system and make it more susceptable to illnesses in general.