Do Black Shell Shrimp Eat Black Hair Algae? My 30cm Tank Experiment

Freshwater shrimp in aquarium

Black hair algae, also known as black brush algae or beard algae, is one of the most stubborn algae types in freshwater aquariums. Many aquarists struggle to control it. I decided to test whether black shell shrimp (Caridina species) could handle a severe infestation in my 30cm office tank.

The Short Answer

Black shell shrimp can eat black hair algae, but only under specific conditions. In my case, 80 shrimp cleared a severe infestation in about two weeks. However, many other aquarists report their shrimp completely ignore this algae type. Your results will depend on several factors.

What Happened in My Tank

My 30cm office tank developed a serious black hair algae problem. The algae covered driftwood, plant leaves, and even some aquarium walls. I did not want to tear down the tank and reset it, so I tried a biological solution.

I introduced approximately 80 black shell shrimp. Within two weeks, the algae was significantly reduced. The shrimp seemed to focus on the algae rather than my plants.

Key Timeline

Day 0: Added 80 black shell shrimp to heavily infested tank
Day 3: Added a new wall-mounted filter to improve water flow
Week 1: Noticeable reduction in algae coverage
Week 2: Tank mostly clear of black hair algae

However, there was a significant downside: by the end of two weeks, only about 10 shrimp remained from the original 80.

Why Results May Vary

My success does not mean black shell shrimp will work for everyone. Several factors likely contributed to my results:

High Shrimp Density

I introduced a very large number of shrimp relative to tank size. With 80 shrimp in a 30cm tank, competition for food was intense. Hungry shrimp may eat algae they would normally ignore.

Limited Alternative Food

I did not supplement with commercial shrimp food during the experiment. Without easier food sources, shrimp had to consume whatever was available, including the less palatable black hair algae.

Algae Condition

Some commenters noticed the algae appeared reddish in later photos and wondered if I had treated it with chemicals. I did not use any treatments. The color change may indicate environmental stress that potentially made the algae more palatable.

Water Flow Improvement

Adding a new filter improved circulation. Better water movement can affect algae health and growth patterns, possibly making it easier for shrimp to graze.

Why Many Aquarists Report Failure

Multiple aquarium hobbyists shared that their black shell shrimp refuse black hair algae. Common observations include:

Shrimp ignoring the algae completely
Shrimp preferring to graze on other surfaces or plants
No noticeable algae reduction despite having shrimp

One user noted their shrimp “only bite plants, don’t eat black hair algae.” This matches the general consensus that black hair algae is not a preferred food source for most shrimp species.

Better Alternatives for Black Hair Algae

If you want reliable black hair algae control, consider these proven options:

Siamese Algae Eater

The Siamese algae eater (Crossocheilus oblongus) is one of the few fish known to consume black hair algae readily. They are effective but can grow large and may become aggressive in small tanks.

Amano Shrimp

Amano shrimp (Caridina multidentata) are larger and more effective algae eaters than black shell shrimp. They have a better track record with stubborn algae types, though they are more expensive.

Manual Removal

Physically removing black hair algae during maintenance often works best for small tanks. Use a toothbrush or algae scraper to brush off affected surfaces.

Address Root Causes

Black hair algae typically indicates:

Low CO2 levels in planted tanks
Poor water circulation
Excess organic waste
Inconsistent lighting schedule

Fixing these underlying issues prevents algae from returning.

If You Try the Shrimp Method

Based on my experience, here are tips if you want to test black shell shrimp:

Use high density: More shrimp creates more competition and grazing pressure
Limit supplemental feeding: Hunger may push shrimp to eat less preferred algae
Monitor shrimp health: Watch for signs of starvation, especially after algae clears
Have a backup plan: Do not rely solely on shrimp if algae persists

Important warning: After clearing the algae, my shrimp population crashed from 80 to about 10. Without their primary food source, many shrimp starved. If your shrimp successfully clear algae, you must either supplement feeding or reduce the population proactively.

Summary

Black shell shrimp can eat black hair algae in some circumstances, but they are not a reliable solution. My experiment worked, but at the cost of most of my shrimp. The high mortality after algae clearance shows that this approach has serious trade-offs.

For most aquarists, combining manual removal with better tank maintenance will give more predictable results. Use proven algae eaters like Siamese algae eaters or Amano shrimp if you want biological control. Black shell shrimp may help, but do not expect consistent results.