Not sure whether I am seeing the beginnings of a skin condition or a new behaviour that I am not familiar with.
You will recall that I have a 300l tank, fully cycled and several years old.
Stock had dwindled to next to none - though the plants were still there (though not thriving because the lighting had failed)
I fed the tank to improve bacteria levels in the three filters that I have installed (it is filtered at least twice what is recommended for this tank)
There is 2-3" natural gravel on the base of the tank and over a dozen slates leaning against the back of the tank to give channels and passages to hide in.
I added 9 mixed cichlids over a month ago - all still there, doing well and growing.
Made 80l water changes every other day for a week then moved to 80l every three days or 40 every other day (or more when I had time). All new water treated with Stress Coat.
All the fish are spreading fins, dropping pectoral fins (no clamping) and interacting socially.
15 days later I added another 10 fish with no ill-effects (taking care to re=arrange all the décor to break up established territories)
Feeding mix of flake, cichlid pellets, snail food (cos its vege and I had some), algae wafers (more for entertainment). Kids put in some cucumber ...no interest from the fish so I took it out.
During this time I swapped out the old fluorescent tubes for a 900mm triple strip of daylight LED lights and 2x 450mm bluemoon LED strips (don't have the blue on often). Daylight on for 12+ hours a day
10 days later I added another 8 cichlids and a synodontis catfish. Again no ill-effects. I week later I found one of the middle 10 newly dead as I took the main filter out to clean it during a water change (I clean only one per water change). It was newly dead because all it's fins were intact and it's eyes were only just clouding over)
All the fish are active, all getting more brightly coloured as they grow (they were 1-2" and some are now up to twice that) all still spreading fins and still no obvious clamping. There is always at least one with an erect dorsal fin... often several (and most of the fish are doing this at some point)
Plants are now doing well in the light(one still has brown leaves...but new growth is green).
There is now algae growing on the slate décor/rear glass (front & side glass kept clean) and they are grazing it from there and from the bogwood that is in the tank.
Kids have tried again with cucumber...and the fish are experimenting with eating it.
I have also put a couple of cubes of bloodworm in ... only once a week and to share amongst the 27 fish now in there.
Also put some skinned garden peas in there occasionally too.
No sugar-coating/salt dusting, no degradation of fins - all have clearly defined edges and some have good colouration. Egg spots are developing on the males. The Blue Peacock is getting quite fluorescent and the Pink Peacock is not far behind. No "velvet".
But - some of the fish are "flicking" ...not all the time. It seems to be the bigger/male ones.
If they had skin irritation I would expect it all the time ...and to be seeing other signs...but it's been over a week since I first noticed.
They do appear to raise all their fins and shudder just before they do this "flicking"
Is it a territorial display?
Is it a different form of behaviour?
I am currently doing 40l changes every other day.
Is there anything else I should be doing?
"Be prepared..... be VERY prepared!" I'm not sure Lord Baden-Powell used the last bit...but it works for me!