Amano Shrimp

Amano Shrimp — named for Takashi Amano, who popularised them as the working animal of the planted tank — are the hobby's most capable algae eaters, and considerably tougher than dwarf shrimp. They tolerate a wide parameter range, live several years, and are large enough that most community fish leave them alone.

They are also the one common shrimp you cannot breed in a home aquarium, and any listing that implies otherwise is worth questioning. The reason is covered in the breeding section below.

Keep them in groups. A single Amano is a nervous, secretive animal that hides; six are confident, active and constantly working over surfaces in the open. Six is a sensible minimum.

They need more space than Neocaridina — 40 litres upward for a group of six. They are also accomplished escape artists, especially when first introduced or when water quality dips: cover the tank properly. A dried-out Amano on the carpet is a common and entirely preventable loss.

Genuinely undemanding by shrimp standards. They handle a much broader range than Caridina like Crystal Reds, and ordinary treated UK tap water suits them in most areas without remineralisation.

The usual invertebrate rules still bind absolutely: no copper, in medication or fertiliser, at any dose. Amano are large enough to survive a great deal, but not that.

Drip acclimatise on arrival over two to three hours. Their size makes them look robust, and they are — but a shrimp that has spent 24 hours in a courier bag has been through enough without a parameter shock at the end of it.

They appreciate good oxygenation and moderate flow more than dwarf shrimp do. A slightly stronger filter is fine here, though the intake still needs guarding.

Amano earn their reputation. They will clear hair algae, black beard algae and general film that most other cleanup animals ignore, and they work at it constantly.

The important consequence: do not over-supplement them. A well-fed Amano stops eating algae. Keepers who add them to solve an algae problem and then feed them daily are often puzzled that the algae remains. Feed lightly, and only when there is visibly little left for them to graze.

When the tank is genuinely clean, offer a sinking pellet or blanched vegetable once or twice a week. They are also enthusiastic scavengers and will find any uneaten fish food.

They can be startlingly assertive at feeding time — an Amano will pick up a pellet and carry it away from smaller shrimp. This is normal and not aggression toward tankmates.

Amano are the easiest shrimp in this hobby to sex, and they use a marker nothing else here does.

Look at the pattern along the flanks. Both sexes carry a row of reddish-brown markings down each side. On a male these are evenly spaced round dots. On a female the lower row is drawn out into longer dashes — noticeably elongated, almost commas. Once you have seen the two next to each other you can sex an Amano across a room.

That marker is reliable, unlike the saddle-and-belly method used for dwarf shrimp. Amano females do develop a saddle and do carry a deeper abdomen, but they are large animals with a lot of body, and the difference is far less obvious than the flank pattern.

Females are also clearly larger — up to about 5cm against 3.5cm — though as ever that only helps with mature animals of similar age.

Worth knowing: sexing them changes nothing practical. They cannot be bred in fresh water regardless of ratio (see Breeding), so unlike dwarf shrimp there is no reason to buy for a particular mix. Get six and enjoy them.

Amano Shrimp cannot be bred in a normal freshwater aquarium. This is a hard biological limit, not a difficulty rating.

Females berry readily and will carry eggs in fresh water without any trouble. The eggs hatch into free-swimming larvae — and those larvae require brackish water to develop. In fresh water they die within a few days, every time. To complete the cycle the larvae must be moved to salt water at the right salinity, raised through several stages on specific foods, and then gradually returned to fresh water as they metamorphose into juveniles.

It is done commercially and by a small number of dedicated hobbyists. It is not something that happens by accident in a planted tank, and it will not happen for you unless you set out to do it deliberately with separate equipment.

Practical upshots: every Amano you buy was either commercially bred or wild-caught, they will never overrun a tank the way Neocaridina do, and a berried female in your tank is not the start of a colony — those eggs will not produce surviving young in fresh water. Nothing is wrong; that is simply the species.

Their size is their protection. At 4–5cm they are too large for most community fish to treat as prey, which makes them far more broadly compatible than dwarf shrimp.

Safe: tetras, rasboras, danios, corydoras, otocinclus, most peaceful barbs, guppies, endlers, and snails of any kind.

Usually fine: bettas and dwarf gouramis, though individual temperament varies and a determined betta will harass them.

Not safe: cichlids, large gouramis, loaches, pufferfish, crayfish, and anything large enough to swallow a 4cm invertebrate.

They coexist perfectly well with Neocaridina and Caridina, and because they cannot interbreed with either, they are the one shrimp you can safely add to a colour-line colony without genetic consequences. They will, however, out-compete smaller shrimp at feeding time.

Escaping. The most common cause of loss, and entirely preventable. Cover the tank, including filter cutouts and cable gaps.

Death shortly after introduction. Usually acclimatisation, occasionally copper. Their apparent toughness leads people to rush the drip.

Not eating algae. They are being fed too much of something else. Stop supplementary feeding for a week.

Berried female, no babies. Not a problem — see breeding above. This is the species working exactly as it should.

Sudden death of a long-held individual. Amano live several years, and an established shrimp dying at three or four years old has most likely reached the end of its life rather than been poisoned.

Pale, milky-white body. Distinct from normal moulting translucency, and usually a bacterial infection. Uncommon, and generally not treatable by the time it is visible; isolate if you can and review water quality.

Amano are not graded — they are a wild-type species kept for what they do rather than how they look, and there are no colour lines to speak of. Price varies with size and source, not grade.

Two things worth checking when buying, because misidentification is genuinely common in this part of the hobby:

Several similar-looking species are sold as Amano, including *Caridina serrata* and various regional relatives. True *Caridina multidentata* have a distinctive pattern of dashes and dots along the flanks — dots along the lower body, and a broken line of longer dashes above. Females carry longer dashes than males, which is also the most reliable way to sex them.

Wild-caught animals are still common in the trade and often arrive in poorer condition than tank-bred ones, with higher first-week losses. It is a fair question to ask a seller, and a good seller will know the answer.

*Caridina multidentata* is native to Japan, Taiwan, Korea and parts of eastern China, in clear, fast-flowing coastal rivers and streams — quite unlike the still, weedy water Neocaridina come from.

The crucial detail is that those rivers reach the sea. Amano are amphidromous: adults live and breed in fresh water, but the larvae are washed downstream into brackish estuaries, develop there through several planktonic stages, and the juveniles then migrate back upstream. That life cycle is the entire reason they cannot be bred in a home aquarium, and it is a fact about their habitat rather than a difficulty rating.

It also explains their care. Fast-flowing water means they tolerate — and appreciate — far more flow and oxygenation than dwarf shrimp. A wide temperature range across a latitudinal spread from Taiwan to northern Japan is why they handle 18–26°C comfortably. And a life spent grazing rock and wood in current is why they are such effective algae eaters and why they lose interest the moment you feed them properly.

Wild populations are under pressure in parts of the range from river engineering and dam construction, which block the upstream migration that the life cycle depends on. A meaningful proportion of the animals in the trade are still wild-caught.

The species was described by Wilhelm De Haan in the 1840s, long before anyone kept it in a tank. Its aquarium history is much more recent and much better documented than most of this hobby's.

Takashi Amano — the Japanese aquarist whose Nature Aquarium style reshaped planted-tank design worldwide — began using them in the 1980s specifically as an algae-control animal, and wrote about them extensively. The hobby named them after him, and the association stuck so completely that the scientific name is now the less familiar one. He is genuinely responsible for their place in the hobby, which is rare enough in this trade to be worth saying plainly.

A taxonomic wrinkle worth knowing when reading older sources: they were widely called *Caridina japonica* for years. That name is now considered a synonym of *C. multidentata*, which has priority.

No colour lines exist and none are likely to. Because they can't be bred in captivity at scale by hobbyists, there has been no selective breeding — every Amano is essentially wild-type, and the animal you buy today looks the same as the one Amano was writing about forty years ago. In a hobby built almost entirely on selective breeding, they are the conspicuous exception.