What is this?

[Aqualady40]

I woke up Tuesday morning and found my gourami fins shredded .. The inhabitants are (in a 20h heavily planted) as follows 3 White Cloud mountain minnows 3 male guppies 6 neon tetras 1 female platy.... I watching the tank this morning and noticed the White Cloud minnows were chasing the neon tetras so I'm kinda wondering if they bullied my gourami......I took her out immediately, put in clean de-chlorinated water with a little salt, did that today to...she is still eating and swimming.

Is this fin rot or aggression?

Link to photo of gourami
http://www.aquariumadvice.com/forums/members/66406-albums11445-picture50331.html

 

[Hholly]

Yikes! I'm betting on aggression. Not sure, but I bet the platy did it.

 

[Aqualady40]

Yikes! I'm betting on aggression. Not sure, but I bet the platy did it.

Really? Platy's are aggressive? Hmmmmm! The only fish that visually show any aggression is the WCM's they chase the neon tetras into hiding and my guppies and platy swim together and the gourami did her own thing

 

[Kimlafeiet]

Ouch. I am going to bet on the Platy as well. I have 2 hi-fin variatus platy's, and they are incredibly territorial in my big 55 gallon. they own the back right corner, and do not share.
Maybe your wcm's need a bigger school to keep aggression down? I have 5 wcm's and 6 neons and they actually school together as a big group.

 

[bud29]

definitely aggression and not fin rot. Fin rot wouldn't happen so suddenly. It's hard to guess the culprit, because male guppies, white clouds, and platys can all AT TIMES be nippy. Yikes!