Aggression Question

[Aqualoon]

As my tank is maturing I'm having some issues with aggression, have lost a few fish now due to this.  Have tried adding more rock work in the tank, taking out rocks, adding more flow (bought 3 Koralia Evo pumps) and it doesn't seem to have made a difference.

I'm wondering if adding more stock would help?  Or what else should I be doing?

[gturmindright]

What size tank? How many fish?

[Aqualoon]

125 Gallon - started with 40 fish, lost 2-3. The fish that I lost I noticed the aggression in the tank prior to the death, meaning...

It was always my thoughts with africans to overstock so that a single fish wouldn't get singled out and could 'get lost' in the crowd so to speak. The fish that I lost were healthy, usually on the larger scale for the rest and very colorful (so it's not like the small/sick fish getting singled out or anything). So, before I lost a fish I would notice some fighting, if they broke apart I would follow them throughout the tank and moments later they'd be fighting again. This is when I stepped in and tried the things in my OP to stop it. Even after doing things the fighting would start back up. Now, I can't be sure it was the same fish(s) fighting after an scape change or anything, but again, they would be on the bigger side, more colorful, etc.

Also something I am noticing now - all the fish pretty much stay on one side of the tank. You could cut my tank in half and you'd get all the fish on one side, and none on the other side. I tried changing up the equipment on these sides to see if they stayed away from the heater or the side with the 2 water pumps but it doesn't seem that way - they just all prefer the right half of the tank, no matter what is or isn't there. They aren't hiding in the rocks at all, and swim above them.

Thoughts?

[...]

What variant are we talking about? How big are they? Wild or tank raised? Grown out from fry together or bought as adults? Ratio?
Not unusual for adult troph males to single out other males to maintain dominance and sole breeding rights within a group.
If you notice others getting damaged or harassed and you have the space, move them out to another tank as spares should you lose your alpha. Or remove the aggressor for a week or 2 then put him back if it is just 1 psycho male.
HTH

[mikevxr]

I have about 25-30 Tropheus in each of my 300 litre tanks. I don't have a lot of rocks only 2/3 pieces evenly spaced along the tank. I do use black round guttering cut to 6" pieces stacked on top of each other as hides for my fish. I haven't had a great deal of issues with aggression but mine have all been raised together since about 1.5". Even when I only had 1 female and 11 males in one tank. I. Have however noticed that my F1 fish seem to be far more aggressive than tank bred fish but could just be the variety (Bemba). Generally if I see a bit too much fighting I just turn the lights off and things seem to calm down, I don't see the Piont in rearranging decor as males will start fighting again to establish new territories. I would watch out for signs of bloat if your fish are getting stressed. A good way to spot this is at feeding time - when you feed them look for any fish hanging back and not eating. Especially if they do it a couple of days running. There are other posts on the site dealing with bloat so it's not the end of the world as easily treated, key however is spotting it early.

Attachments: