Agressive gourami

[modernhamlet]

Last Sunday, I added 5 Harlequin rasboras to my 29g.
Everything was fine. They adjusted nicely.
On Tuesday, I added 5 more rasboras.
On Wednesday, one of them died. I chalked this up to stress, travel, and the fact that it was a Petsmart fish.
The week continued and everything seemed fine. The rasboras were doing their thing (schooling, playing, looking great), the gourami were doing theirs (primarily courtship behavior).

Yesterday, I noticed one rasbora (a smaller one) being ostricized by the others. It looked very weak, but had no obvious damage to it. It died later that night.
I got up this morning to find yet another rasbora hiding in the thick plants.

But this time, one of his eyes looks like it was destroyed.

I think my Pearl gourami (you know... the "peaceful" gourami? ) may be the culprit. Could this be something other than physical attacks? The water parameters have never strayed from stable and ideal (pH=6.7, NH3=0, NO2=0, NO3=10-20).

I don't want my rasboras to be picked off, one by one!

What's going on?

 

[Morrgan]

I hear this sort of thing isn't unusual. I haven't been able to find any certain cause, but several people on other forums have complained that their harlequins are fine for a week, then start to die off one by one. Someone suggested a (undefined) viral disease, others thought it might simply be that sometimes harlequins are of "bad quality" due to bad breeding.

Have you seen the pearl harassing the harlequins, by the way?

I just got 12 harlequins yesterday, so after reading about all that I can't help but feel a bit paranoid and worried about them... I hope someone else can give a better answer than mine.

 

[modernhamlet]

The male pearl does harrass the rasbora, but not to excess. I'll sit and watch the tank for 2 hours and he'll go on a 5 or 10 second chase maybe 2 or 3 times in that span, usually when the offending fish gets too close to his "spot" in the tank. I've never seen him actively hit or damage one though. What I'm concerned about is what happens after the lights go out.

This is quite frustrating, since I've worked so hard to give these fish great conditions (fishless cycled, clean water, lots of plants, overfiltration).

I think I'm going to have to set up the 10g and move the Gourami into that temporarily. They really want to spawn, but can't effectively in the community tank (the HOB filter prevents bubblenest building). But I don't really want a bunch of fry either, as I have no way to keep them longterm and wouldn't know how to get rid of them once they're big enough anyway.

So confused.

 

[jams.alaskan]

Hi Modern Hamlet-
I've got a lovely pearl and a harlequin, never seen agression - never. I'd be surprized if your pearl could even catch the little fellas - or want to. I'd look to other causes if you aren't seeing attacks yourself. Right now my guy is a singular (waiting to find "healthy" ones to add). Really, I think that Morggan might be on to something there......

ALASKA

 

[modernhamlet]

Just to give you an idea of how confused I am:

In the top back corner you have the injured and probably dying rasbora.

Just 6 inches below him, in the thicket of Dwarf Hygrophila, there are 2 rasboras spawning under several leaves!

I wish I could get a better look at the injured fish to know if it's collision damage or something internal like popeye.

Edit: That fish is clearly a victim of blunt force trauma, either by being struck by a fish or slamming itself into something hard. Crap.

 

[modernhamlet]

I had to euthanize the injured rasbora.

No sooner had I done this, when I noticed another rasbora isolated from the school. This is officially a pattern. And it may be the other rasboras doing it. Does anyone know if a school will reject or drive away their weakest member due to illness or injury? Can other fish sense that sort of thing?

I'm stumped. From a school of 10, I'm down to 7... probably soon to be 6.

Are there really no ideas out there? Should I just wait for this to "take its course"? Should I move the sick/isolated fish? The gourami? Should I just give up?

Help, please?

 

[motherof6]

My Gouramis tend to be very territorial. If you re-arrange your tank a bit before adding new fish they usually leave the new ones alone staking out new territories. Other-wise the new fish wander in an already claimed area and bam. I did notice too they seem more aggressive at night. Maybe they know they are not being watched.

 

[modernhamlet]

Has anyone experienced this with their neons or other small schooling fish? I think this may be it.

http/freshaquarium.about.com/cs/disease/...neondisease.htm