Calothrix is a reef aquarium nuisance that can spread if early signs are ignored.
Identification: Dark filamentous cyanobacterial tufts or mats in lower-flow zones or nutrient-imbalanced areas.
Treatment / Management: Manual siphon removal, flow correction, nutrient control, and correction of underlying husbandry issues.
Prevention: Maintain stable nutrient ratios, avoid detritus accumulation, and quarantine new hardscape when practical.
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