I have an attack fish, but which one is it?

[gfink]

I had:
2 red wag platys (both male, one died after severe tail damage a week ago, other hides now)
5 zebra danios (fine)
2 dwarf gouramis (mboth male, 1 just died today and looked like he had damage around his mouth. Both kinda pale looking, they have definately lost color. Shorter feelers like they have been nipped)
3 Albino catfish (fine)
4 Otos (fine)
Apple Snail (getting huge)
4 red Eye Tetras (fine)

I used to think it was the red wag platy since he always swam high in the tank like he owned it, but now he just hides. I have not seen any aggressive behavior. The gouramis nipped eachothers tails, but I never saw damage, and I had them for a year.

Any ideas?

29 gal, heavily planted
Temp=74°
Ammonia= 0
Nitrite= 0
Nitrate= 10-20 ppm
pH= 7.0

 

[Cherry]

That's weird gfink. Platys seem pretty docile, danios are fast but don't really seem mean, catfish mind their own bussiness...I've noticed my red eyes sometimes chase and nip eachother but nothing serious (and I can't imagine an apple snail being sneaky enough ). The dwarf gouramis I had were pretty aggressive to eachother males and females...to the point that I had to separate them. Maybe someone else with more danio / platy experience will chime in, but for now the gouramis would be my first suspision.

 

[Zagz]

I would have to think that the gouramis are the most likely culprits as well. The other fish you have are fairly docile and I can't imagine they would be able to get the best of the gouramis.

 

[gfink]

Odd thing is that the gouramis are shy. They hide a lot and are the last to come out for food(lately...they used to be more bold). Well, now that there is only one gouramis, do you think things will settle down? And why after a year does this start? I even replanted 2 weeks ago trying to break up any territores that were established.

 

[lyquidphyre]

I would think if the gourami starts to perk up some... then it was prolly the two gouramis fighting and being territorial and if one regains color it means he is less stressed and prolly the culprit

 

[Tiffi]

And why after a year does this start? I even replanted 2 weeks ago trying to break up any territores that were established.

That might be the reason they started doing that. They had to reestablish their territories, so things got ugly. If you break up territories you just ignite a new fight, since they won't just give their space up but try to get the best "new" space and the battle begins. You see I think as well it was the gourami.

My female dwarf gourami is even getting so ignorant right now to swim into the Kribensis' cave, which bring their fry back there every night. Soon she must get her behind kicked.

My male dwarf gourami kept swimming around the otos when I got them new. Swimming closer and closer all around them until be pushed them away, followed them and so forth. Later he decided that the spawning Kribs might be a better hobby for him. Having a 70gal tank to swim in he always had to swim around the 5" radius around the cave and fights started all the time. I finally had to separate him!

 

[gfink]

I would think if the gourami starts to perk up some... then it was prolly the two gouramis fighting and being territorial and if one regains color it means he is less stressed and prolly the culprit

You are probably right. The remaining gouramis has regained his bright colors. I guess that after a year of living together, they just decided to go at it. They both lost their color and started fighting.