What Makes Amano Shrimp the King of Algae Eaters
Amano shrimp (Caridina multidentata, formerly Caridina japonica) were popularized by legendary aquascape artist Takashi Amano, who used them extensively in his famous Nature Aquarium designs. Their effectiveness as algae eaters comes from two advantages: their large size (adults reach 4–5 cm, roughly double the size of cherry shrimp) and their extraordinarily voracious and persistent feeding behavior. While cherry shrimp graze leisurely on biofilm, Amano shrimp actively hunt down and systematically devour algae growths.
Amano shrimp are particularly effective against the algae types that most other fish and invertebrates ignore: hair algae (filamentous green algae), thread algae, staghorn algae, and early-stage black beard algae (BBA). They are not reliably effective against mature, established BBA colonies, but they will prevent new growth from gaining a foothold. In planted tanks where algae outbreaks are a constant challenge — especially in high-light, high-CO2 setups — Amano shrimp are an indispensable biological control tool.
In Cambodia's aquarium trade, Amano shrimp are less commonly stocked than cherry shrimp but can be found at specialty planted tank shops in Phnom Penh and Siem Reap. Their price is typically 3–5x higher than cherry shrimp, but their algae control value makes them worth the investment for any planted tank keeper. Unlike cherry shrimp, Amano shrimp cannot breed in freshwater — their larvae require brackish to marine conditions — so the population stays fixed at what you purchase.
- ✦Stock 3–5 Amano shrimp per 50 liters of planted tank volume for meaningful algae control impact
- ✦Amano shrimp are escape artists — ensure your tank has a tight-fitting lid or a reduced water level near the top
- ✦Newly added Amano shrimp will not eat algae for the first 24–48 hours as they acclimate — do not remove them during this period
Hair Algae and BBA — What Amano Shrimp Can and Cannot Fix
Hair algae (long, tangled green threads) is the number one problem in planted tanks, and Amano shrimp are arguably the best biological control available. In a moderately stocked group, they will visibly reduce a hair algae outbreak within five to seven days, working around the clock to pull apart and consume the filaments. Tanks that maintained a permanent Amano shrimp population rarely develop serious hair algae problems because the shrimp intercept small outbreaks before they become tangled masses.
Black beard algae presents a more complex challenge. Fresh, soft BBA — the fuzzy purple-grey variety just beginning to colonize plant leaves — can be controlled by hungry Amano shrimp, especially if the algae is first spot-treated with a hydrogen peroxide injection using a syringe (turn off circulation, apply H2O2 directly to the BBA, wait 30 seconds, then resume flow). The peroxide weakens the algae cell walls, making it much more palatable to Amano. Mature, wiry BBA colonies are generally too tough for Amano shrimp to consume.
Thread algae and staghorn algae fall between these two extremes. Amano shrimp will graze on both given time, particularly if they are slightly underfed on supplemental food. The key to maximizing their algae-eating efficiency is not to eliminate supplemental feeding entirely — starved shrimp become stressed and die — but to feed only every two to three days in small amounts, keeping the shrimp hungry enough to prefer algae over waiting for pellets.
- ✦Spot-treat BBA with a 3% hydrogen peroxide injection before adding Amano shrimp — weakened BBA is consumed much more readily
- ✦Feed Amano shrimp only every 2–3 days in planted tanks to keep them motivated to graze on algae between feedings
- ✦Remove large tangled clumps of hair algae by hand first, then let Amano shrimp clean up the remaining attachment points
Amano Shrimp vs Ghost Shrimp — Which Should You Choose?
Ghost shrimp (Palaemonetes paludosus or similar local species) are commonly available in Cambodia as feeder shrimp and are significantly cheaper than Amano shrimp. On paper they seem like a budget alternative for algae control, but in practice their algae-eating effectiveness is far lower. Ghost shrimp are opportunistic omnivores that prefer soft food — fish food, dead matter, and biofilm — over algae. They will rarely tackle the problematic algae types (hair, thread, BBA) that Amano shrimp consume eagerly.
Size is another major difference. Adult Amano shrimp at 4–5 cm are substantially larger than ghost shrimp (2–3 cm), which gives them access to more food and makes them more visible and interesting in the aquarium. Amano shrimp are also more tolerant of a wider range of water conditions, while ghost shrimp can be inconsistent in their tolerance. However, ghost shrimp have one key advantage: they are widely available as a native Southeast Asian species across Cambodia and are cheap enough to use as feeders for large predatory fish.
For planted tank algae control specifically, the investment in Amano shrimp is justified. For a large predatory fish tank where algae control is secondary and the shrimp will likely become food anyway, ghost shrimp offer better value. If your goal is a clean, healthy planted aquascape, there is no comparison — Amano shrimp perform the role decisively and reliably in a way that ghost shrimp simply cannot replicate.
- ✦For a 60-liter planted tank, a group of 8–10 Amano shrimp will outperform 30–40 ghost shrimp for algae control
- ✦Ghost shrimp are excellent feeders for larger fish but are not a meaningful algae management strategy for planted tanks
- ✦If you cannot source Amano shrimp locally in Cambodia, ask aquarium importers — they are regularly available through Bangkok distributors
Feeding Amano Shrimp in Tanks Without Sufficient Algae
A clean, newly set up planted tank may not have enough algae to sustain an Amano shrimp colony. In this situation, supplemental feeding is essential to prevent starvation. Amano shrimp accept the same foods as other freshwater shrimp: algae wafers, blanched vegetables, spirulina powder, and high-protein pellets. In the absence of algae, feed every two to three days and observe the shrimp closely — a properly fed Amano shrimp is active, transparent (not opaque white, which indicates stress), and moves around the tank purposefully.
A useful strategy is to cultivate a "algae tile" — a spare piece of glass or rock placed near a window or under strong light that accumulates green algae over days. Drop this into the main tank when needed as a supplemental algae source. Amano shrimp will cover the tile within minutes and graze it down completely. In Cambodia's strong sunlight, cultivating algae on a spare tile outside takes only two to four days during the dry season.
Amano shrimp should not be kept in tanks where other fish out-compete them for food. Fast, aggressive feeders like cichlids and large goldfish will eat all the food before Amano shrimp can access it. Amano shrimp are best paired with small, peaceful community fish — tetras, rasboras, small Corydoras — or kept in a species-only planted tank where they can feed at their own pace.
- ✦Cultivate an algae tile (glass or rock under bright light) and rotate it into the tank as a natural food supplement every few days
- ✦If Amano shrimp turn opaque white or stay hidden for days, they are likely stressed from lack of food — increase feeding frequency immediately
- ✦Pair Amano shrimp with small peaceful fish only; avoid any fish large enough to swallow a 4 cm shrimp
Long-Term Amano Shrimp Care and Lifespan
Amano shrimp are one of the longest-lived freshwater shrimp species, capable of reaching 3–5 years in optimal conditions. This longevity is unusual in the shrimp hobby, where most Neocaridina species live 1.5–2 years and Caridina bee shrimp slightly longer. The key to maximizing Amano lifespan is stable water parameters, varied nutrition, and avoidance of the two most common killers: copper toxicity and oxygen depletion.
In Cambodia's warm climate, oxygen saturation decreases as water temperature rises. At 30°C, water holds significantly less dissolved oxygen than at 24°C. Since Amano shrimp are active, large-bodied shrimp with relatively high oxygen demands, ensuring strong surface agitation is critical in warmer months. A sponge filter alone may be insufficient in a dense planted tank on hot days — add an air stone or position a powerhead to break the surface during the April–May heat peak.
Amano shrimp rarely breed in captivity because the larvae require brackish water with a salinity of 25–30 ppt for development before returning to freshwater as juveniles. This complex lifecycle means your colony size will decrease slowly over years as individuals age and die. Plan to replenish the colony every three to four years with a new purchase, or build a relationship with a specialty importer who can source them regularly.
- ✦Add surface agitation (air stone or spray bar) during hot months — Amano shrimp need more oxygen than cherry shrimp at elevated temperatures
- ✦Amano shrimp do not breed in freshwater — plan to purchase replacement shrimp every 3–4 years as the colony naturally ages
- ✦A lifespan of 3–5 years is achievable with stable water, varied food, and zero copper exposure — they are a long-term investment in tank health