Random Gourami Behavior??

[BettaGal]

I just saw my dwarf gourami chillin in the bamboo field like he enjoys, only this time, he was vibrating his dorsal fin?? He vibrated it twice for like two seconds and then just went on his merry way tending to his "garden" which I constantly see him doing. What does the vibrating behavior mean? It's probably normal, but I've never seen anything like this.

 

[BettaGal]

And if anyone can remind me the name of this plant, it would be most helpful. The fish store didn't have water sprite and the lady recommended this, and she's the one that actually sounds like she knows what she's talking about. I forget the name of it, but it's my gourami's favorite plant. He's always cleaning it and biting off stringy things on it and tending the rocks I have holding it in the sand.

 

[BettaGal]

Google didn't give me anything on a dwarf gourami vibrating his dorsal fin, so I need a little help finding out what it means. Is he happy? Is he ticked off? Is he just weird? Is he wanting to mate? What does this behavior mean?