Microsorum sp. 'Blue'

Microsorum sp. 'Blue' is a trade variety named for the notable blue-green or teal iridescence visible on the frond surfaces under certain lighting conditions, particularly when illuminated from above with bright, full-spectrum LED or T5 fixtures. The iridescence is caused by thin-film light interference in the frond epidermis and is most pronounced on young, actively growing fronds. Older fronds typically revert to a standard deep-green colour.

Beyond its visual novelty, 'Blue' is a well-behaved, moderately sized Microsorum reaching 20–30 cm, and requires care broadly similar to other members of the genus. It attaches to hardscape via a rhizome, tolerates low light, and grows without CO2. The blue iridescence is best displayed under moderate, full-spectrum lighting, so slightly higher light levels than typically used for Java ferns are recommended to maintain the optical effect. It is a collector's item and a striking conversation piece in any planted tank.

Light: Low to moderate; slightly higher light than standard Java fern enhances the blue iridescence on young fronds. CO2: Not required; CO2 supplementation improves growth but does not significantly affect the iridescent effect. Fertilisation: Bi-weekly liquid micronutrients; adequate iron supports healthy frond colour and iridescence. Placement: Position where fronds are directly illuminated from above to maximise the blue iridescent effect. Propagation: Divide rhizome into sections retaining 2–3 fronds each; attach to hardscape with thread or glue gel.