so, what is the real reason for Cory's shoaling???

[Magnum Man]

so, a 25% water change on this tank today, and the Cory shoal loosened up significantly again, so I continue to expect that it's all the Cichlid "presence" in the water... hormones, pheramones, and or "by products" of some sort, build up, and cause the Cory's to be alarmed, even though there is no physical challenges between the Cory's, and the various Cichlid population.... I will continue to do larger water changes, more often, to see if things get back to "normal"

 

[MaloK]

Your experiment tends to demonstrate that plants are indeed not taking up everything in the water and some products still build up with all the plants you have.

How much do you have to add to regularly top off the tank ?

 

[Magnum Man]

in that tank almost 10 gallons per week, estimated 5 gallons for evaporation, and 5 gallons for plant take up , so with the plant use, that's maybe 25% water change every week or two... so it may still be on the low side, even if the plants were taking in the fish byproducts... I need to get my volumes up...
those numbers work for all my tanks, but the one with so many Cichlids

 

[Magnum Man]

interestingly, a day after this last water change, I'm still seeing more normal Cory shoaling, and activity level, however they aren't on the bottom anymore, now they are mostly swimming mid water level ( which doesn't really seem "normal" )

they had, pre water change, been pretty tightly compacted in the lower right corner, on the bottom... roughly where the blue acara is, in this 1st picture...
they are pretty mobil right now, and in a much looser shoal, and not near the bottom, except at feeding time... they look healthy, and I'm not seeing anything physical keeping them off the bottom???