[marten]

I've lost a few fish from my mixed Malawi tank over the past few months. It seems to me that it's from increased aggression I've seen lately. I just want to run the typical scenario by you all to make sure I'm not missing some kind of disease or other problem i should be dealing with.

What i see is this: A bullied fish ends up breathing hard, it looks like the fish version of hyperventilating. If it continued for more than a day I've isolated the fish and sometimes they get better. Other times they've kept breathing that way and I lost them eventually.

Have a rightly diagnosed this as aggression related, or should I be considering something different?

thanks in advance for your help!

 

[DJRansome]

Usually it is easier than that...but unless the death is due to blunt force (never happened to me) IME aggression deaths are ALWAYS due to illness. Harassment leads to compromised immune system and then a disease like bloat.

The most obvious symptom is the fish lurking under the surface and behind heaters and filter intakes. They stop eating and eventually die.

 

[marten]

Is it possible I'm seeing something similar, except I'm seeing the heavy breathing instead of bloat?

 

[DJRansome]

It may be a different afflication due to compromised immune system. Are the fish that end up dying lurking under the surface or near filter intakes or heaters? Are they eating right up until the day they die?

Any clear or white thready feces?

 

[marten]

In some cases they lurked behind the filter, or they wiggled as far as they could inside a large fake plant. There were no white thready feces. If I had them isolated they stopped eating one or two days before death or else they perked up and were fine after. If I didn't isolate the fish I would find it dead earlier on, and to me it looks like the tank will sometimes just harass a weak fish to death.

The only white feces I've seen was with a healthy fish, but it was immediately followed by normal feces.

 

[marten]

I should add that all the fish I lost were missing parts of their fins and had been roughed up before.

 

[DJRansome]

The trick is to deal with aggression so no fish becomes weak and promptly when you see fin nips and missing scales. Or the lurking behavior. Too many males and not enough females?

 

[marten]

I have one male per group, but these are the problems I've seen:

The male red shoulder was the smallest of his group and he did a lot of damage working his way up the pecking order. I started with 1M:4F but I'm down to 1M:2F. It looks like injuries are healing now with no new damage.
The Male yellow lab is the most dominant fish in the tank, but the Male Acei is starting to challenge him now, and this seems to stress the whole tank at times.
Female yellow labs seemed very rough on each other, I've seen evidence of mouthlocking. For the Labs I started with 1M:4F after weeding out the extra males, and I'm down to 1M:1F + 5 juveniles now.

Acei seem fine 1M:5F
Deep water Haps seem ok after adding more females. 1M:4F (they might actually all be females)

 

[DJRansome]

Add females to any group with less than 4. If the red shoulder was killing females keep an eye on him in case you have to swap him out for a kinder male.

Not that common for females to harass each other...are you sure some of the labs were not sub-dominant males? Labs are hard to sex.

 

[marten]

Thanks very much for your help DJ! I will keep an close eye on the Male red shoulder then. And yeah all the female labs spawned quite regularly and the one remaining adult is holding now.