Hrm. Gourami Aggression?

[pharasalia]

I started a 2nd tank at the end of last week, speed cycled it using Bio Spira, and following the directions, added my stocking.

Stocked with:
1 neon blue dwarf gourami
6 black neons
3 dwarf cory cats

Everyone was doing great. The water quality was testing very good. The neons were schooling, the corys going along the bottom and doing their thing, and the gourami seemed okay. Depending on how the lights were in the room, if he saw his reflection, he'd go along the tank wall that try to get the other gourami he thought he was seeing. He paid no attention whatsoever to his tank mates.

Some time in a 6.5 hour span after lights out, when I was in bed, that changed. I woke up to find 2 of the neons dead, one near a plant, the other floating at the surface and the one at the surface was getting pecked at by the gourami. The other 4 neons were sticking together in the center of the tank, the cory cats were fine. The gourami was either pecking at the dead neon or trying to get his reflection.

I immediately tested the water again:
pH 7.8
Ammonia 0.5
Nitrite 0
Nitrate @5

These black neons were not the tiny neons, they were very nice sized. They seemed to be doing fine for hours beforehand... but I can only think of 2 possible reasons they might have died.. One, they are neons and not so hardy as most people experienced and for whatever reason they died naturally overnite. Two, the gourami killed them.

Any ideas?

 

[Tinajo]

I've always thought dwarf gouramis were peaceful unless 2 males were housed together. Maybe you just had some sick/weak tetras?

 

[pharasalia]

That is what I had always heard too, but it isn't the case. They are semi-aggressive, imo. Its a coin toss as to what you will end up with when you add one to your tank unless you have ample time to watch it first. Males w/ males is pretty much a guarantee of a fight unless its a large tank, that is true.

I read several places that they were peaceful and good for community tanks. Then I looked again and found several places where they were listed as semi-aggressive. Now, based upon my own experiences, I believe they are most definitely semi-aggressive.

This was not a case of weak or sick tetras... not matter how often that happens. These tetras were very healthy and happy before the gourami went on his biting spree. He killed 2 neons overnite while I slept w/in a 6 hour period or so. Having no choice, I went to work. When I got home from work another neon was dead, one of the corys was dead, and another of the corys and 1 neon wounded. Obvious that they were attacked. The wounded neon was missing his tail fin, he died a few hours later. The wounded cory had a wound on his side behind his fin. He tried to swim around but when he swam it was in a spiral and mostly he just laid on his side. He has since passed away. So all in all, I lost 6 fish to this gourami. I witnessed his aggression after I was home from work. It is just very unfortunate that he didn't display aggression on that first nite, before I went to bed... then all my fishies would still be alive.

I rushed him back to the pet store last nite and exchanged him for something I knew wouldn't eat the neons - a few platies. I couldn't even think of putting something in there that might hurt them again. The pet store also very kindly replaced 3 of the dead neons (am still short one =/) and also 2 of the dead cory cats.

Just a warning... watch newly introduced gouramis until you know they are peaceful. I have one in my other tank and he's hasn't hurt a single fishy.

 

[fishlore101]

I always kept two dwarf gouramis together (but not two males). My blue gourami chases his reflection on the tank when the other gourami is hiding. The neons could have just been weak or sick. I think that when there is a dead fish in the tank other fish will try to peck at him or eat him. I would watch him closely and if there is any aggression I would take him out and put him in a different tank.

 

[pharasalia]

Yes, they do. And it was my first thought upon finding the first 2 dead neons that it was just as possible that they had died naturally and become food.

However, the rest of the scenario did not play out that way.

These neons were in no way sick or weak, and it was most definitely the gourami visciously attacking them, biting off tail fins, giving my cory cats bad wounds in their sides... of course, this happened while I was at work and could do nothing. I lost 4 neons and 2 cory cats to the gourami in less than 48 hours.

Fish, like people, all have different personalities. While many places will read/tell you that the gouramis are only aggressive to 2 males being together, this simply isn't the case. When I researched my fish, I found many places labelling them peaceful and didn't look further. I have since looked further and found other places where they are described as semi-aggressive and on forums where other people have also had them attack and kill small fish. We can't really generalize about gouramis being peaceful. I have one that is. This one definitely wasn't. Its a dice toss as to what you are going to get personality wise most certainly. At least, a designation of semi-aggressive would give people a heads up that their new gourami could be a fish killing machine...

Either way, I took that gourami back immediately upon coming home and finding more fish dead and wounded and obviously not from being sick/weak but from being attacked and having fins bitten off and their sides torn open.

 

[Star_Rider]

Did I read that right? ammonia at .5??

neons actually tend to be sensitive to water issues. A .5 ammonia would lead me to suspect this could be the culrpit.

did you do a water change?

is this tank cycling?

gourami's are labrynth fish thus capable of gulping air..

if the neons and other fish are stressed they may have become targets for the gourami.

tho drarves tend to be more friendly..this does not preclude them from having impulses you may find among the gouramis.

 

[rsanz]

I have an inkling that it wasn't the gourami at all, but the ammonia that killed your neons. Neons are extremely susceptible to poor water conditions. Your tank isn't cycled yet, so I would wait to get more neons until your tank reads 0 for both ammonia and nitrite, and around 5 for nitrate.

 

[jm1212]

the black neons may have jsut died. just because a fish was pecking at a dead one doesnt mean that he killed it. when fish die in a tank, the other fish say "hey, free food," and go in for a good munch.

if your tank is cycling, that could also be a culprit to the death of the black neons.

yes, if he saw he reflection in the mirror of the tank glass, he would become aggressive, but that is because he thinks that another amle is invading his territory.