So, after a week of intensive feeding for the new ones, nitrates were at 60-70ppm. Changed half the water, and cleaned a cannister in the afternoon. Skipped dinner too.
After daylights went off begging stopped. They know not to expect food in "twilight time". Then all the botia turned attention to eachother. The fresh water and better flowing cannister had triggered something.
After lights dimmed, one of the yoyos started flashing on the sand, making a big cloud, and they immediately started a 4-way yoyo swirly fight, lasting about 10 min. Later they argued with the skunks, boes males and the labeo. An hour later, normal behaviour again.
Meanwhile, the new big clown came out. On the sight of her, the leading clown raced to the other side, to start flashing on all the rocks near their sittingspot. I expected a fight, they always fight on a foodless day. Especially now the big one is coming out more and more. But no, the big one flashed on the same rocks, in the same spots. Clown #2 then did the same, and #3 aswell. No clicking, no greying out. Just flashing the same square inch, one rock after another, one clown after another. It happend in sessions of 1 to 3 minutes each, after which they would sit in caves, rest, and start the game again. The small ones didn't take part in this, just squabbled amongst themselves.
all that at the same time was good fun for spectators. But why is there so little info on this social/territorial flashing? I searched forumtopics for flashing, randomly read trough a few and found just 2 persons telling (over) concerned loachkeepers that flashing is not necessarily a sign of a deadly disease. Only 1 person told about the social flashing.
Because of me learning from other topics this week, i paid more attention to the flashing. It happens a lot. But no fish scratches himself continiously, or show any other discomfort. The clowns flashed at least 200 times all together. No flashing at all when the "display" was over.
I dont have much experience with disease, but i figure that a fish with a few parasites on the skin would scratch himself very frequently. One scratch doesn't mean the fish is contaminated with "waterfleas"

. Just like i do scratch on a muskitobite freuquently, but one scratch not meaning i am bit by a moskito. Please correct me if i am wrong.
Also i think a different word should be used for "itchy flashing". How about scratching? Or a term must be found for the "social flashing". They clearly look different. Flashing already sounds like a "showing-of-to-others". Of course this is just my personal opinion.
having said all this, i do NOT wish to promote carelessness around the fishies, just point out the difference, to help in judging loach's conditions. The search showed 15 pages of topics, of which probably half were panicking over nothing.
I think flashing may need a topic of its own, or even an article on the main website. For that, i would need help from more experienced loachkeepers though.
Anyway, next w.c. i will have the good camera charged for use in case they do it again. It was good fun to see.