Internet search has brought me back here a few times now, but none seem to be showing what I'm seeing! These lines are physical damage on the leaves; however my flow is borderline non existent, so I just can't see it being that.
Also, this damage didn't exist (I think) before adding a bunch of Otocinclus. I think my Oto's are giving my Heteranthera zosterifolia a hard time!
Any suggestions? I'm tempted to take them back to the shop, and wave bye to the £40 I spent on them!