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While watching my fish tank today, I couldn't help but notice that it looked as though my Harlies are fighting.

I've noticed this a couple times before, but nothing as intense as it was today. There are 7 of them all together and it looked as though only two of them were being the troublemakers.

About 3-4 of them would be swimming along side by side, and then one would turn inward on the other and look as though they were getting into a little fight and then take off in different directions. Then the instigating fish would take off for another target. This went on continuously for at least 5-10 minutes. It was finally broken up when I added their dinner into the tank. However, whether or not they still continued to do it after I stopped watching (obviously) I don't know.

So, could this actually be fighting or is it just simply their way of playing? I don't believe I have ever heard anything about Harlies fighting with one another the way I saw them today, so I wanted to run the situation past all of you to see what you guys all thought.

Thanks to anyone who can shed some light on this situation!

If you look closely at most schoals of tetras and barbs they are always 'fighting' amongst themselves, even fish such as neons do this. i think it is their way of establishing a heirarchy in the group, in fish such as your harly's it is nothing to worry about and i dont think these fish ever cause any actual damage to each other, the larger specimens just like to exert their authority over the littler ones. Hope this helps.

Thanks!

I was getting a little worried about them since it was getting rather intense looking last night. I figured that they were probably just working out some social things and it didn't look as though they were hurting eachother. So, it's nice to know that it isn't anything to really worry about.

Harlequins, in particular, form very strict hierarchies. If this seems to be a constant problem, you may consider adding another harly or two, because the more fish their are, the more structured it becomes, and the aggression should be distrubuted more evenly.

Joe Potato

if u r to add others its best if there all the same size

by any chance is the most aggresive one the most colorful? in my school the most aggresive is the most colorful.

20 Gallon Long:
Aquaclear 300
2 Bolivian Rams, Mikrogeophagus altispinosus: Gumby and Pokey

Mine do this all the time. I have 5 males and 1 female (bad luck of the draw, I guess). Anyway, before the one female mates with any of them, the boys kind of get into their little horn-locking sessions to determine who gets her that day. I suspect this is occuring in your tank, as well. In two years, I've never had to separate them. I do keep melafix and pimafix on hand and when a scale is missing or one looks roughed up, I dose it a few days to make sure it doesn't fungus. I often dose it at the first sign of heavy fighting, as someone's bound to get scraped up.

That sounds rather like the way my Lemon Tetras behave Cory_Di, except that my Lemons adopt specific 'landmarks' from which to display and joust with each other. Do Harlequin Rasboras do this too? Or do they work out their social hierarchy within the shoal in open water?

I've noticed that fishes with high-contrast fin markings are more apt to engage in this sort of display. And since Harlequins have prominent red dorsals and caudals, chances are they use them for signalling in the same way as my Lemons use their black-and-yellow fins for signalling. Let me know if the Harlequins display in open water or adopt 'landmarks' Lemon Tetra style so I can update the database

Panda Catfish fan and keeper/breeder since Christmas 2002

YOu mean, do they fight around certain territories? I've seen those territories change. It could be one leaf on Monday, then a nook between plants the next. They don't seem to hold on to a specific territory all week.

Ah. Only my Lemons tend to pick a site an stick with it. Which is why I;ve labelled the behaviour I've seen "part time territoriality", because they take off and shoal, then suddenly the males think to themselves "it's time I reasserted my place in the pecking order with the chicks, heh heh heh" and suddenly, the males are taking up battle stations and issuing challenges to each other. As far as I can se, they always choose the same landmarks.

Silver Tip Tetras are especially noted for this. A feature of theie behaviour noted way back in the 1960's by the Dutch aquarist and aquarium author J.M. Lodewijks (I still have one of those vintage books of his!). And, when I acquired Silver Tip Tetras during my teenage years, they performed right on cue, just as dear old Mr Lodewijks said they would. I even planted my aquarium deliberately to try and give them a choice of landmarks so I could see this in action.

Another fish that I have in my "part time territoriality" list is my Beckford's Pencils. But they're wacky. Their push wrestling is bizarre.

Harlequins, from your desription, differ here. They're asserting their pecking order in the shoal, but are not attached to 'landmarks' as such. I have to say it would have been quite a surprising development if they had shown a preference for specific landmarks for this behaviour, they would have been the first of the shoaling Cyprinids I've heard of to do this. In which case, Cory_Di, you would have had a genuine 'first' to your name, and the textbooks of the future would be referring to you!


Panda Catfish fan and keeper/breeder since Christmas 2002

I started with three. I am up to 15 harlequins now. I can't get enough of these little charmers. And they get along beautifully Seems the more you add, the more they school, the more peaceful they are. Enjoy!

Mine have also displayed these actions, but I have mistaken it for breeding displays as it usually involves only two specimens in particular.