This is nana plant. Sorry for my ignorance, I tot nana plant don't need put any additional fertiliser...
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Anubias is a hardy plant and can tolerate alot of different condition. But it is still a plant afterall.
Normally, the plant absorb nutrients from the water through its leaves. The plant still need the normal range of nutrients like NPK and other trace elements. Because it usually grow slower in low light, the nutrients need is also lower. In higher light and or co2, it will grow faster and need more nutrients. If nutrients is lacking, sign of deficiency will be displayed.
The hole may also be due to snails like apple snails or fish. Low possibilty but it really depends on your tank setup.
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