fishtank.camNeo shrimp bowl · 5.3 gal

Low techNeo shrimp bowl

A bowl that runs itself.

A 5.3 gallon glass bowl of soil, plants and blue shrimp. No filter, no heater, no CO2.

01The glass

A bubble of glass.

Hand-blown, 12 inches tall and 13 wide, with a 7.5 inch opening.

02Soil

Soil first.

Plain potting soil that feeds the roots from below.

03The cap

An inch of sand.

Just enough to hold the soil down.

04Hardscape

Stone and wood.

Seiryu stone and small wood: somewhere for moss and Anubias to hold on.

05Plants

Then the green.

Four stem plants, crypts, Anubias and Christmas moss.

06Water

Filled slowly.

Poured gently, so the soil stays where it is.

07Floating

Salvinia on top.

Shade, cover, and a head start on algae.

01Low tech

No filter. No heater. No CO2.

  1. Plants as the filter

    Plants take up ammonia, the toxic part of waste, straight from the water.

  2. Slow on purpose

    Months to fill in; a trim about once a month.

02The Walstad method

Built from the bottom up.

Named after Diana Walstad, who keeps shrimp in bowls like this one: soil, sand, plants, water. No filter.

Waterpoured in slowlySoilabout 1 inchSand capabout 1 inchRootsfeed herePlants take up ammoniabacteria in the soil do the restTop up what evaporates
  1. 01 · Soil

    Soil at the bottom.

    About an inch of plain potting soil, with no added fertiliser, soaked overnight. As it breaks down, it feeds the roots and gives off the CO2 the plants use.

  2. 02 · Sand cap

    Sand on top.

    Just enough sand to hold the soil down. Kept thin, so oxygen still reaches the soil: soil with no oxygen kills roots.

  3. 03 · Roots

    Plants go in first.

    The plants are set into the wet soil, then the sand goes over their roots. Stems stand up through the cap; roots stay down in the soil, where the food is.

  4. 04 · Water

    Water, slowly.

    Poured over a hand so the soil stays put. The first cloudy water is changed once or twice, until it runs clear.

  5. 05 · Clean water

    Plants are the filter.

    Plants take up ammonia, the toxic part of shrimp waste, and prefer it to other food. Bacteria in the soil break down the rest.

  6. 06 · Water changes

    Almost none.

    In Walstad's own bowls: a little pruning, and topping up what evaporates. The exception is the first few weeks: new soil gives off ammonia, so the shrimp wait (here, about a month) and the water is tested.

03Plants

Each plant has a place.

StemLudwigia repens
StemRotala rotundifolia
StemWater wisteria
StemLimnophila aromatica
RosetteCryptocoryne wendtii
On stoneAnubias
On woodChristmas moss
FloatingSalvinia

04Nitrogen cycle

Waste in. Clean water out.

Plants take ammonia WasteShrimp NH3Ammonia NO2Nitrite NO3Nitrate PlantsGrowth BacteriaBacteria

  1. New soil, first weeks

    New soil releases ammonia. The shrimp wait about a month.

05Neocaridina davidi

Blue, by design.

Blue Dream, bred from Neocaridina davidi. In the wild they are mottled brown.

20 to 30 eggsunder her tail About 1 mma tiny copy, no larva About 1 inchgrown

  1. A grow-out bowl

    The colony breeds here, and its young restock the showcase tank.

00Livestock

Blue, by the dozen.

  1. 01 · One shrimp

    Blue Dream shrimp

    Neocaridina davidi

    A deep blue line, bred on purpose.

  2. As a shrimp

    Selectively bred from Neocaridina davidi; wild ones, from Taiwan, China, Korea and Vietnam, are mottled brown. Under about an inch; females are larger.

  3. Behaviour

    Grazes all day, picking the film of algae and bacteria off plants, stone and glass.

  4. Its job here

    Keeps the bowl clean of film and leftovers.

  5. Facts

    Size
    Under about 1 in
    From
    A bred line of a shrimp from Taiwan, China, Korea and Vietnam
    Water
    65 to 85 °F

    Wikipedia, Neocaridina davidi; The Shrimp Farm, Blue Dream care

  1. 02 · The colony

    The colony

    Neocaridina davidi

    How one becomes many.

  2. Eggs

    A female carries 20 to 30 eggs under her tail.

  3. No larva

    They hatch as tiny copies of the adults, about 1 mm long, with no larval stage, so the colony grows in fresh water.

  4. One colour

    Mixed colour lines give mixed or dull young, so the bowl keeps one blue line.

06Timeline

Plants first. Shrimp later.

  1. NowSetting up

    Soil, sand, stone and wood in; the plants arriving.

  2. About a monthPlants grow in

    Roots spread, the biofilm builds.

  3. ThenBlue Dream shrimp

    One pure colour line, with ramshorn snails.

07Side by side

One house. Four ways to live.

07The tanks

Five tanks, one house.

00Gear list

What it is made of.

The gear list
  • Glass bowl5.3 gal, hand-blown, 13 in wide
  • Potting soilAbout an inch, no added fertiliser: feeds the roots
  • Sand capAbout an inch, holds the soil down
  • Seiryu stone and small woodSomewhere for moss and Anubias to hold on
  • Stem plantsLudwigia, Rotala, Water wisteria, Limnophila
  • Cryptocoryne wendtiiA rosette in the front
  • Christmas mossOn the wood
  • SalviniaFloating, for shade and cover
  • No filter, heater or CO2The plants and the bacteria do the work