Just today I have noticed a couple of my danios and a couple of my platys doing this strange skimming or glancing off of plants leaves, its not a continual process just seen them do it a few times thats all.
Never noticed it before, first time today.
Not noticed any white spots or anything like that.
I have a 29g heavily planted and fairly heavily stocked with small community fish.
nitrate 40ish ppm theres nothing I can do about it, i get that right out of the tap.... my tank is heavily planted but still nitrates remain high...unfortunately.
A couple of weeks ago, I added an incompatible fish to the group, who caused major stress for very one concerned, it was in the tank 4 days and then I removed it and returned it back to the LFS, but during this time there was lots of upheaval in the tank, with nets and hands and evil fish. In the end I had to trap the newcomer in a makeshift prison to keep it away from the other fish. this nightmare climaxed with a nitrite spike out of nowhere, never had issues with this prior to that weekend of problems. the fish were gasping at the surface, I nearly had a heart attack it was horrid. I got rid of the fish back to the store, and did several water changes dosed with prime to return params. back to normal. since then everyone has been fine.... until, today I notice this behaviour.
This is the only thing I can think of that could have caused any issues.
Is this behaviour indicative of some kind of disease taking hold? or do fish do this sometimes? for another reason.