World of ShrimpHow many cherry shrimp can live in a 20-liter tank?
Published · Updated · 3 min read
Short answer
Stocking guides suggest about 10 cherry shrimp per US gallon, or 2.5 per liter, for healthy growth and breeding. A 20-liter tank holds about 5.3 gallons, so that is roughly 50 shrimp. You don't need to buy that many: start with about 10, and the colony will grow by itself.
What the guidelines say
Shrimp guides don't agree on one exact number, but they land in the same area:
| Source | Guideline | For a 20-liter tank |
|---|---|---|
| Shrimp and Snail Breeder | 10 per gallon (2.5 per liter) for the best growth and breeding; 15 per gallon as a practical upper limit | About 50, and no more than about 80 |
| Shrimp Science | 10 to 15 per gallon | About 50 to 80 |
| The Shrimp Farm | 75 to 125 per 10 gallons is "not uncommon" | About 40 to 65 |
The numbers for a 20-liter tank are worked out from each guideline, using 20 liters = about 5.3 US gallons. In liters the math is easy: 20 liters × 2.5 shrimp per liter = 50 shrimp.
Shrimp Science adds that small tanks should stay near the lower end, around 10 per gallon, because their water changes faster than in a big tank.
Other tank sizes
Shrimp and Snail Breeder gives this chart for dwarf shrimp such as cherry shrimp:
| Tank | Best for growth and breeding | Practical upper limit |
|---|---|---|
| 5 gallons (about 19 liters) | 50 | 75 |
| 10 gallons (about 38 liters) | 100 | 150 |
| 20 gallons (about 76 liters) | 200 | 300 |
Why not more?
Crowded shrimp usually survive, but they don't do as well. Shrimp and Snail Breeder describes a 90-day study on Neocaridina kept at three densities. Survival was similar in all groups, but the shrimp in the most crowded groups grew smaller. Smaller females carry fewer eggs, so a crowded tank also breeds less.
Oxygen is another limit. Warm water holds less oxygen than cool water, so a crowded tank in summer is at the most risk.
How many to start with
About 10. Aquarium Co-Op suggests at least 10 shrimp for a breeding colony, because a group that size very likely includes both males and females. Flip Aquatics suggests starting a colony with 10 to 20.
From there, cherry shrimp breed on their own in a good tank. A female carries about 20 to 30 eggs at a time, so the colony can grow quickly once it settles in. See our breeding guide.
What changes the number
- Plants and biofilm. A mature, planted tank is full of biofilm, the thin layer of algae and microbes shrimp graze on. More food means room for more shrimp.
- Other animals. Fish and snails also produce waste and eat the same food, so a mixed tank holds fewer shrimp.
- Maintenance. Regular small water changes and careful feeding matter more than the exact headcount.
If the colony grows faster than you would like, you can give shrimp to other hobbyists or move some to a second tank.
Sources
- Shrimp and Snail Breeder: How Many Shrimp Per Gallon? Calculator and Science
- Shrimp and Snail Breeder: Red Cherry Shrimp: Care, Diet and Breeding
- Shrimp Science: Shrimp Tank Shapes and Sizes
- Shrimp Science: Red Cherry Shrimp care guide
- The Shrimp Farm: Caring for Red Cherry Shrimp
- Aquarium Co-Op: Care Guide for Cherry Shrimp
- Flip Aquatics: Cherry Shrimp Guide
- U.S. Geological Survey: Dissolved Oxygen and Water
Keep reading
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How to set up a 20-liter shrimp tankEquipment, substrate, plants, water and cycling, in the order you need them.
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Cherry shrimp breeding: males, females and berried shrimpHow to tell males from females, what berried means and how to raise the babies.
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What and how often to feed shrimpWhat shrimp eat, how much to give them and how to avoid overfeeding.