Peaceful 75g Gourami Tank With 3 Pearl Gouramies - safe to add more?

[AquanautMD]

Hi,

Like the title says, I've decided to start a peaceful gourami tank. My tank is 75 gallons and well planted. I have 3 varieties of gourami, all of which have been in the tank for about a week now: Pearl Gouramies, Honey Gouramies, and Sparkling Gouramies. For the most part, everyone is peaceful and gets along well, especially the latter two. However, I did notice some seemingly aggressive behavior from my pearls the other night. One of them seemed to be chasing another around every time it came in sight of it, to the point the one being chased one swim to the other side of the tank and stay there. Every time he/she would wander back, they would be chased again. Since then I haven't noticed that behavior again, and have even seen all 3 pearls schooling peacefully together quite a bit.

I'd like to add 3 more pearls to my tank as there is plenty of space, so my question is, what causes the behavior I saw in my pearls the other night, and will it be safe to add the additional pearls?

 

[mbkemp]

I believe gourami to be fairly easy to sex. To me, it is either two males sorting out ranking or a male chasing a female for the other reason

Take a look at their dorsal fins. A female will be more rounded a male will be larger and come to more of a point