Best Algae Eaters Compared: Shrimp, Snails and Fish
The comparison
| Species | Best at | Adult size | Min tank | Group |
|---|---|---|---|---|
| Amano Shrimp | The best all-round algae eater. Eats hair algae most others refuse. | 2.0″ | 10 gal | 3+ |
| Bristlenose Pleco | Heavy-duty on wood and glass. Needs driftwood in the diet. | 5.0″ | 29 gal | single ok |
| Cherry Shrimp | Constant grazers on soft algae and biofilm; also a colourful colony. | 1.0″ | 5 gal | 6+ |
| Mystery Snail | Moderate algae eater, mostly a detritus cleaner. | 2.0″ | 5 gal | single ok |
| Nerite Snail | Unbeatable on hard green spot algae. Lays harmless white eggs. | 1.0″ | 5 gal | single ok |
| Otocinclus | Soft green film algae on glass and leaves. Needs a mature tank. | 1.5″ | 10 gal | 6+ |
Match the cleaner to the algae
| Algae type | What works |
|---|---|
| Green film on glass | Nerite snails, otocinclus |
| Green spot (hard dots) | Nerite snails — almost nothing else touches it |
| Hair / thread algae | Amano shrimp |
| Black beard algae | No animal reliably eats it. Fix CO₂ and flow, spot-treat |
| Brown diatoms (new tanks) | Otocinclus, nerites — but it usually clears on its own |
| Blue-green 'algae' (cyanobacteria) | Not algae, not eaten. Blackout and fix nutrients |
The uncomfortable truth
Algae is a symptom, not a species problem. It appears when light and nutrients exceed what your plants can use. Adding cleaners to a tank with a nutrient imbalance is treating the smoke rather than the fire. Reduce the photoperiod to 6–8 hours, increase water changes, add fast-growing plants, and feed less — then add cleaners for maintenance.
Also: an algae eater added to a spotless tank will starve. These animals need either an established algae supply or deliberate supplementary feeding with algae wafers and blanched vegetables.
Frequently asked questions
What is the best algae eater for a freshwater tank?
Amano shrimp are the best all-rounder because they eat hair algae that most other species ignore. For hard green spot algae on glass, nerite snails are the only reliable option.
Do algae eaters eliminate algae completely?
No. They control it. Algae growth is driven by light and nutrients, so the real fix is reducing the photoperiod to 6–8 hours, increasing water changes and adding fast-growing plants.
Will algae eaters starve in a clean tank?
Yes. This is the most common way otocinclus and amano shrimp die. Supplement with algae wafers, blanched courgette or spinach if the tank has little natural algae.
What eats black beard algae?
Almost nothing eats it reliably. Siamese algae eaters sometimes do when young. The practical fix is spot-treating with hydrogen peroxide or liquid carbon and correcting CO₂ and flow.
Next steps
Written and reviewed by Marcus Rivera. See our methodology for how figures on this site are derived.