Anyway, I have thought about it more, and think it is worth posting.It was late one evening when we were at the shop doing some of our annual stock take. I was trying to guesstimate the number of each species on the loach system, and noticed that the powerhead in the tank containing the Annamia and Acanthocobitis botia had become blocked and there was no flow coming from it. I should point out at this point that our built-in filtration produces very good flow, but I have extra powerheads in many of the Balitorid tanks to give even more current. I quickly set about removing the protective cage underneath this powerhead which had become clogged with debris, and in doing so a fair bit of muck ended up in the tank, hence my reluctance to post the video (our tanks aren't normally full of bits!). So having sorted the powerhead and given the fish a huge step-up in flow, I resumed my stock take. Literally a couple of minutes later I was about to start counting the fish in a tank not far away from the Annamia tank when two of them caught my eye. They were swimming up into the flow together and twisting round each other. There was quite a bit of general argy bargy, but there was also moments where one fish would appear to nibble the dorsal surface of the other and then they'd swim up into the current together again. I watched this for a good 10 minutes (didn't want to move and frighten them) before I decided I had to try and get my camera to record some of it. I crept back with it and took the following short clip which shows some of this behaviour. Unfortunately a lot of the quality seems to have been lost with the photobucket hosting, my original shows much more detail. (Please turn the sound down to avoid hearing my camera refocusing):
http://s88.photobucket.com/albums/k183/ ... CN0412.flv
This is different to usual Annamia squabblings, and I feel the sudden dramatic increase in flow (not sure how long the powerhead had been clogged for) triggered them off.
Apologies again for all the bits, but as I said, I had literally just cleaned the powerhead cage and restarted it when this behaviour started, so there was no real time for the tank to clear.
Emma
Resistance is futile. You will be assimilated.
It makes me want to bring some of these home into a tank set up with moderate flow and have extra powerheads ready to turn on at some point to simulate what happened there. But there is no more room at the inn... 
I have secret plans! 
