Amano Shrimp UK: Algae-Eating Specialist Every Planted Tank Needs

What a planted tank needs — and why Amano shrimp are the answer

Every planted aquarium that runs for more than a few months develops algae. This is biology, not failure: photosynthetic organisms in a warm, lit, nutrient-rich environment will grow. The question is which organisms dominate.

The three algae types most UK planted tanks fight are: green hair algae, green thread algae, and diatom film. Plecos ignore them. Otocinclus eat a little diatom film. Cherry shrimp graze biofilm but mostly avoid structured algae. The species that genuinely eats all three, reliably, is Caridina multidentata — the Amano shrimp.

An Amano shrimp showing the diagnostic dotted line running along the flank — the key identification feature separating Caridina multidentata from similar-looking species like Caridina babaulti. Photo: Tropical Fish Co warehouse.

I'm Sophie Harding, the site's shrimp specialist. I keep Amanos in three of my twelve species tanks — they're the maintenance layer in my breeder planted tanks, quietly controlling algae between water changes.

The amphidromous life cycle — why you can't breed them

This is the single most important biological fact about Amano shrimp, and almost every UK hobby guide skips it.

Caridina multidentata is amphidromous: its life cycle requires movement between freshwater (where adults live) and brackish water (where larvae develop). The seminal lab work on this was done by M. Tsuda in 1990 ^[2].

What happens in the wild:

1. Adult females release larvae into freshwater streams
2. Larvae drift downstream in the current to coastal estuaries
3. Larvae need brackish water (roughly 1.015 specific gravity, equivalent to 25% seawater) to complete four developmental moults
4. After metamorphosis, juveniles migrate upstream back to freshwater
5. Juveniles become adults in freshwater streams and the cycle repeats

What happens in your aquarium:

1. Adult females release larvae into freshwater
2. Larvae have no estuary to drift to
3. Larvae die within 3–5 days

There is no way to breed Amanos in a standard aquarium setup. Specialist hobbyists have succeeded with a separate brackish rearing tank but it's a significant project — not a casual outcome of keeping the species.

Commercial stock comes from either wild-caught Japanese and Taiwanese specimens or farm-bred operations that maintain the brackish larval stage in dedicated hatcheries. Every Amano in the UK trade has been through one of these two supply chains ^[1].

Amano vs cherry — picking the right shrimp for your goal

Head-to-head: Amano vs Cherry

The planted-tank answer: keep both. A 90 L planted tank with 9 Amanos + 20 cherries is a complete shrimp crew — Amanos control hair algae, cherries graze biofilm and breed to sustain the colony. The species don't interbreed (different genera), so the tank stays genetically stable.

What Amanos actually eat — field observations

From my own tanks and from the observational research community ^[8], here's the realistic rank of what Amanos will and won't graze:

Will happily eat:

• Green hair algae
• Green thread algae
• Staghorn algae (moderately)
• Diatom film on glass and plants
• Leftover fish flakes + sinking pellets
• Dead plant matter
• Blanched vegetables (courgette, spinach)
• Sinking shrimp wafers

Occasionally nibble:

• Black beard algae (BBA) — rarely; don't rely on them
• Green spot algae
• Soft algae on driftwood

Ignore completely:

• Cyanobacteria (blue-green algae) — you need a 3-day blackout to kill this
• Hard, crusty algae on rocks
• Healthy plant tissue

The single best supplementary food

Once your tank is algae-clean, Amanos still need something to graze. The go-to supplement is a sinking shrimp wafer (Shrimp King, Hikari Shrimp Cuisine, or Bacter AE) — 2–3 times a week, one wafer per 10 Amanos. Drop at lights-out; the shrimp emerge from plant cover to feed.

Habitat in the wild — what their stream looks like

Amano shrimp side view. The dotted line pattern is the diagnostic — slightly compressed to a dashed pattern in younger specimens, becoming more distinct with age. Photo: Tropical Fish Co warehouse.

Caridina multidentata inhabits fast-flowing streams on the Japanese and Taiwanese islands and parts of mainland China, typically within 50 km of the coast (because of the amphidromous life cycle). Natural streams:

• Substrate: smooth river pebbles, some sand
• Flow: moderate to fast; well-oxygenated
• Temperature: 15–25 °C seasonal range (hence their tolerance of unheated UK tanks)
• pH: slightly alkaline (7.2–7.8) due to mineral-rich catchment geology ^[1]
• Vegetation: streamside mosses, submerged hardy plants (anubias-like species in tropical regions)

For an aquarium that mimics this habitat:

• Smooth river gravel or fine sand substrate
• Moderate flow from sponge or gentle canister filter
• Room temperature tank (no heater needed in most UK homes)
• Any planted tank layout — they're not biotope-purists

Stocking table — how many Amanos per tank size

One of the most common mistakes we see: buyers order "a couple" of Amanos for a 60 L planted tank and wonder why the algae keeps growing. The right stocking ratio is higher than most UK sources suggest.

One Amano per ~8–10 L of planted-tank volume is the working algae-control ratio. Less = incomplete control. Much more = food-competition stress.

Algae-type table — what Amanos will and won't touch

Use this table when planning an algae crew. For a fully- controlled planted tank: Amanos (hair/thread) + bristlenose pleco (green spot) + Siamese algae eater (BBA) covers every category.

Size-selection table — what you're actually buying

If shops are selling under-2-cm Amanos at adult prices, they got a cheaper juvenile import and are pricing at adult market rates. Ask for larger grade if possible.

Watch: Amano shrimp grazing in a mature planted tank

Tank setup + welfare protocol

The 5 things an Amano tank needs

1. 60 L minimum for a functional group of 5 Amanos
2. Sponge filter or canister with pre-filter sponge to prevent juvenile shrimp being sucked into intakes
3. Live plants — at least 30% plant coverage for hiding and grazing surface
4. Stable parameters — weekly 10–20% water changes, no sudden shifts
5. No known shrimp predators — no puffers, no large gouramis, no adult angelfish

Our welfare-first shipping protocol

• APHA-compliant live-animal carrier (licensed live-animal courier)
• Insulated polystyrene box with temperature-matched heat/cool packs by season
• Oxygen-charged double bags with air-space sized for 36-hour transit minimum
• Species-isolated quarantine for 7 days minimum before shipping
• Live Arrival Guarantee — photograph unopened bag within 2 hours, full refund/replacement ^[6]

The thing we explicitly don't do: ship via Royal Mail. It's not regulated for live animals; casualty rates on Royal Mail shrimp shipments run 30–50%. Any UK seller using Royal Mail is operating outside the APHA framework.

UK community + resources

The amano-shrimp community in the UK is smaller than the cherry-shrimp community but more technical:

• UK Aquatic Plant Society (UKAPS) — amano husbandry is a regular topic in the shrimp subforum
• Aqua Design Amano UK distributors — carry the ADA books where Takashi Amano's philosophy is documented ^[4]
• Facebook "UK Planted Tank Keepers" — Amano sightings in aquascape contest posts
• Practical Fishkeeping — features Amanos regularly in aquascape spotlights ^[7]

When your Amano shrimp arrive

Amanos ship better than cherries because of their larger body size and slower osmoregulation rate. Our standard protocol:

1. Open in a dim, quiet room
2. Float the sealed bag for 20 minutes — temperature equalisation
3. Drip-acclimate for 60 minutes at 1 drop per second — slower than fish, matches shrimp osmoregulation
4. Net into the tank (don't pour bag water into the display)
5. Lights off for 2 hours
6. No feeding for 24 hours — Amanos will start grazing existing algae within hours

First-week survival on our Amano shipments over the last 12 months: 99.6%.

Ready for more?

For cherry shrimp care alongside Amanos, see our cherry shrimp guide. For the fish-based algae specialist (black beard algae control), the Siamese algae eater guide.

The amano shrimp care guide covers breeding attempts (specialist project) + long-term colony management. Broader invertebrate husbandry is in the shrimp keeping care guide.

Full range: shrimps & crustaceans hub.