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Some algae is good — shrimp graze on soft biofilm all day. When one type coats the glass, plants or moss, it signals an imbalance in light, nutrients or maintenance. Pick what you see below to get the likely cause and a fix that is safe for Neocaridina and Caridina — no copper algaecides, no risky chemicals.
Shrimp tank algae types, causes and shrimp-safe fixes
| Algae type | What it looks like | Likely cause | Shrimp-safe fix |
|---|---|---|---|
| Green spot | Hard green dots on glass and slow leaves | Too much light, low phosphate, slow plant growth | Shorten light to 6–8 h, scrape glass, add fast growers |
| Hair algae | Short green fuzz on moss and plants | Excess light + excess nutrients, low CO2 balance | Trim affected moss, reduce light intensity, 10–20% weekly water changes, add Amano shrimp |
| Thread algae | Long thin green strands drifting in flow | Ammonia spike, overfeeding, new tank imbalance | Remove by twirling with a toothbrush, cut feeding, check filter, test ammonia/nitrite |
| Staghorn | Grey-green branching tufts on edges and filter outlets | Low flow, organic waste buildup, fluctuating CO2 | Clean filter, improve flow, vacuum debris, trim badly covered leaves |
Shrimp-safe rules for any treatment: never use copper-based algaecides, never dose hydrogen peroxide or Excel-style products directly on shrimp, and change only one thing at a time so parameters stay stable.
FAQ
Will shrimp eat these algae?
Neocaridina and Amano shrimp graze soft hair and thread algae but ignore hard green spot and mature staghorn. Treat shrimp as cleanup help, not the cure — fix the light and nutrient cause.
Should I do a blackout to kill algae?
Avoid full blackouts in shrimp tanks. They stress shrimp and crash plants. Shorten the photoperiod to 6 hours and dim the light instead.
When is algae a water quality warning?
Sudden thread or staghorn blooms after deaths, overfeeding or a missed water change often mean ammonia or organics are up. Test ammonia, nitrite and nitrate before anything else.
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