Hmmm, I had the photo attached, but anyway, this area totally looked like dirt... but maybe it’s overhanging plants? Could it be that the “leaks” are...
That does look like it is something besides a color change. If it is hard to the touch, I would say it is viral, like carp pox and it should go away...
After going around and around on picking a water pump myself, I reluctantly bought a Flowfriend Pro, a variation of the standard Flowfriend pump and...
What I read/was advised (I think from this forum) was low protein food, in fewer frequencies so they get enough to live on but not enough to produce...