What's eating my microsorum pteropus 'narrow'?

Java fern 'Narrow' is as herbivore-resistant as the species type, with its elongated strap leaves rarely touched by fish or snails. Algae — principally black beard and green spot — remains the main threat. Poor water circulation along its long narrow blades creates algae hotspots. Keep flow moderate and nutrients balanced.

Dark tufts on leaf edges and tips, particularly in areas with fluctuating CO2 Spot treat with Excel; improve flow; add Siamese algae eaters or Florida flag fish

Hard green discs scattered across the narrow blade surface in bright light Shorten photoperiod; raise phosphate slightly; use nerite snails

Very minor pitting on aged or decaying leaves; healthy tissue is unpalatable Manual removal; assassin snails if population is large