I use liquid carbon (Easy Life Carbo, like Excel) 2 ml / day to induce plant growth. But now only 1 ml / day, more on this later. I have a 24 gal tank. I've also dosed potassium, nitrogen, iron and phosphate in the past, but always within the parameters (however, I don't have a potassium test so don't really know how much of that is in my water).
I recently acquired 4 otocinclus macrospilus, today I found one lying dead. I thought they didn't have enough food to eat, so I dashed to the LFS and got some Hikari wafers. Previously I had tried blanched cucumber, but only my sewallia ate that.
So, where I'm getting is this: will the previous use of liquid fertilizers affect fish detrimentally? And otos in particular? For example, my PO4 was too much (something above 3) compared to nitrogen (also 3), so I stopped dosing PO4.
FYI, the 24 gal planted tank has apistogramma borellii harem (1+2), 6 x dwarf pencilfish, 3 otos (NOW :( and a sewallia lineolata. I'm NOT planning to have anymore fish in there.