Shrimp in a jar: keeping shrimp without a filter
A planted jar of cherry shrimp is one of the most charming small setups in the hobby, and it can work without a filter, heater or air pump. It works because the plants do the filtering, and that only holds if the jar is big enough, heavily planted, lightly stocked and very lightly fed. This guide covers how to set one up, what to expect in the first weeks, and the limits that decide whether a jar thrives or crashes.
How a filterless jar works
In a filtered tank, bacteria in the filter turn shrimp waste into less harmful compounds. In a jar, that job falls to the plants, which take up ammonia and nutrients as they grow, and to the bacteria and biofilm on every surface. Aquatic ecologist Diana Walstad describes this approach in her guide Small Planted Tanks for Pet Shrimp: in her setups, red cherry shrimp live in planted one-gallon glass bowls with no filter, heater or special foods. The balance is fragile, though. Too many shrimp, too much food or too little plant growth, and waste builds faster than the plants can use it.
Which shrimp work in a jar?
- Neocaridina such as cherry, blue dream and yellow shrimp are the usual choice; they tolerate the small swings a jar can't avoid. See cherry shrimp care.
- Caridina such as crystal red and Taiwan bee shrimp need soft, stable water and are a poor fit; see Caridina vs Neocaridina.
- No fish. Even small fish eat baby shrimp and add waste a jar can't handle.
Size, container and lid
- About 1 gallon (about 4 liters) or more. Walstad uses one-gallon bowls; bigger is more stable. Tiny jars swing fastest in temperature and water quality.
- Clear glass with a wide mouth makes planting and maintenance easier.
- A loose lid, not a sealed one. A lid resting on top slows evaporation and keeps shrimp from climbing out while still letting air in. Sealed "closed ecosystem" jars are a different, much riskier idea and aren't covered here.
Substrate: soil or inert
The Walstad method puts a thin layer of potting soil under a sand cap: no more than about an inch of soil (roughly 2 cups, moistened and left overnight in her recipe), capped with about a cup of sand. The soil feeds the plants, but it also has a startup cost: Walstad warns that newly submerged soil releases ammonia and uses up oxygen for the first weeks, so the jar needs time before shrimp go in, ammonia testing, and possibly some aeration at first.
An inert substrate such as plain sand or fine gravel, with easy plants that feed from the water, skips the soil's ammonia phase but grows plants more slowly. Either way, avoid active soils made for Caridina, which change the water chemistry. Our best substrate for shrimp guide compares the options.
Plants and light
Plant heavily; the plants are the filter. Fast, easy plants that tolerate cool water work best: floating plants, mosses, hornwort and similar stem plants all pull waste from the water as they grow. Walstad recommends at least 12 hours of light a day. Use a small LED or bright indirect light, not a sunny windowsill: direct sun can overheat a small volume of water in hours and fuels algae. Our best plants for a shrimp tank guide lists easy choices.
Water and the startup wait
- Use a dechlorinator that handles chloramine; Walstad also recommends one that neutralizes heavy metals, because shrimp are sensitive to them. See can shrimp live in tap water.
- Wait a couple of weeks after setup so plants can root and any soil ammonia can pass, and test ammonia and nitrite before adding shrimp. Our how to cycle a shrimp tank guide explains why.
- Acclimate slowly. A small jar has little buffer; see how to drip acclimate shrimp.
How many shrimp in a jar?
Start small. Owners commonly report starting a one-gallon jar with around five cherry shrimp, and a jar that breeds will fill up on its own. If numbers climb, move some out before waste outruns the plants. Our how many cherry shrimp per gallon guide gives figures for filtered tanks; treat a jar as needing far fewer.
Feeding
Overfeeding is the most common way a jar fails. Shrimp in a planted jar graze biofilm and algae all day, and Walstad's shrimp get no special foods at all. If you feed, give a crumb-sized amount once or twice a week and remove anything left after a few hours. See best shrimp food for food types.
Temperature
Cherry shrimp handle a range of room temperatures, and Walstad notes they can survive water as cool as about 55 °F, though plants stop growing at that point. The bigger risk in a jar is a fast swing: a hot room, a sunny window or a cold draft changes a gallon of water far faster than a large tank. In winter, Walstad adds a small heat source to her bowls; see nano shrimp tank heaters.
Maintenance
- Top off evaporation with dechlorinated water; if your tap water is hard, many keepers top off with RO or distilled water, because evaporation leaves the minerals behind.
- Make small water changes, using conditioned water matched in temperature; our shrimp tank water change guide covers how much and how often.
- Trim plants so they keep growing, and remove dead leaves.
- Test now and then for ammonia and nitrite, and whenever shrimp act oddly.
When to add a filter or air
Add a small air-driven sponge filter if ammonia or nitrite shows up, the water turns cloudy or smells, shrimp hang near the surface or stop moving, or the colony outgrows the jar. A sponge filter is cheap, safe for babies and grows extra biofilm. See shrimp-safe filters and quietest air pumps. If shrimp are already dying, work through why are my shrimp dying.
Track it
A jar changes faster than a tank, so a simple record helps. The free Maintenance Schedule printable keeps top-offs, water changes and trims on track, and the Water Parameter Log on the same page records test results.
Frequently asked questions
Can shrimp live in a jar without a filter?
Cherry shrimp and other Neocaridina can, in a heavily planted jar of about a gallon or more with very few shrimp and very little food. The plants take up waste in place of a filter. Caridina such as crystal reds are a poor fit.
How many shrimp can I keep in a 1-gallon jar?
Start with a few. Owners commonly start a one-gallon jar with around five cherry shrimp and let the colony grow, moving some out if numbers climb faster than the plants can keep up.
Do shrimp in a jar need an air pump?
Not usually, if the jar is well planted and lightly stocked. Add an air-driven sponge filter if ammonia shows up, the water clouds, or shrimp gather near the surface.
How often should I feed shrimp in a jar?
Very rarely. In a planted jar they graze biofilm and algae, so a crumb-sized amount once or twice a week is plenty, and some keepers feed nothing at all. Remove leftovers within a few hours.
Do I need to change the water in a shrimp jar?
Yes, but gently. Top off evaporation and make small water changes with conditioned water matched in temperature, and test for ammonia and nitrite now and then.
Should a shrimp jar be sealed?
No. A loose lid that slows evaporation and stops shrimp climbing out is fine, but a sealed jar cuts off air exchange and is much riskier.
Sources: Diana Walstad, Small Planted Tanks for Pet Shrimp (updated May 2023, dianawalstad.com): one-gallon planted bowls, thin soil under a sand cap, heavy-metal-neutralizing conditioner, the soil startup period, no filter, heater or special foods for red cherry shrimp, cool-water tolerance and day length; Shrimp Tank Hub's cherry shrimp care, cycling and filter guides and their references; recurring owner reports (r/shrimptank, 2024–2026).