help - bugs are eating my plants

[BlueAbyss]

Don't suppose you could get a pic of the holes in the leaves? That would help a lot, and also does the damage happen at night (do you actually see the insects, what type of bug are they etc.)?

Careful with the neem oil, it can be quite toxic to aquatic life. I use it to take care of certain outdoor infestations but Parrot's Feather (Myriophyllum) in particular doesn't like the overspray. There were no fish in the barrel (literally or figuratively lol) so I don't know how it affects them.