Anubia nana not doing well

I've had an ongoing problem with someone eating my new anubia leaves. My tank looks like a vegetable buffet when new leaves appear in effort to deter the fish from eating them. I've gotten up at all hours of the night with flashlight in hand to spot the culprit but to no avail. I have 5 plants. that were doing great until something started munching on them.

So the question is, the older leaves are curling and deteriorating and generally looking like crap! I've pulled them from the gravel and let them float hoping this may help. Oh, the question...is the nibbling of the leaves causing the plant to use nutrients in the older leaves to repair the new leaves?

Relevant info:
J. fern, corkscrew val, crypt., J. moss, wisteria is all doing fine.
I dose with 1ml flourish every other week with 30g water change.

Thanks djlen! It definitely appears to be potassium according to the chart. The new leaf growth is normal and if the fish doesn't eat the whole leaf, it grows in fine with just a portion missing.

90 gal, gravel only, no CO2, 4-4'bulbs. Fish include: (2)zebra danios, (2)mollies, (3)swords, (3)platies, (4)ottos, SAE, (7)botia sp., (7)cardinal tetras, (7)rummynose tetras, (2)praecox/(2)bosemani rainbows, (4)congo tetras, (5)harlequin rasboras, (2)hillstream loach.

If #'s mean anything, I have 5 A. nana, 7 J.fern, 2 Wisteria (turning into 5!), 4 C. vals, a small planting of crypts~10 or so leaves.