Shrimp tank lighting: how many hours of light shrimp need, and what kind
Dwarf shrimp don't need a bright light. They graze biofilm and algae, find food by smell and touch, and are active day and night. The light in a shrimp tank is mostly there for the plants, for the biofilm and algae the shrimp eat, and for you to see them. That changes the question from "how much light do shrimp need?" to "how much light do my plants need, without growing more algae than the shrimp can keep up with?"
Do shrimp need light at all?
Shrimp need a regular day and night cycle, like most animals, but not intense light. What light does in a shrimp tank is grow things: plants, the biofilm on every surface and the soft algae shrimp graze. A shrimp-only tank with no live plants can run on a short, dim light period. A tank with mosses, Java fern, Anubias and floating plants needs a bit more, though still far less than a high-tech planted aquascape. We haven't found a controlled study that pins down an ideal photoperiod for cherry shrimp, so the hour ranges below come from planted-tank and manufacturer guidance, not shrimp trials.
How many hours of light?
Sources disagree, which is useful to know before you trust any single number. 2Hr Aquarist, a planted-tank reference, recommends about 5–6 hours for a new tank or any tank fighting algae, 7–8 hours for a stable low-tech planted tank, and 8–9 hours for a stable CO2-injected tank, and says that beyond about 12 hours you mostly get more algae with no extra plant growth. Aqueon, a light and aquarium maker, notes that the tropics where most aquarium animals and plants come from have about 12 hours of light a day, and suggests about 12 hours for planted tanks and 8–10 hours for tanks without live plants.
| Shrimp tank | Common starting point | Notes |
|---|---|---|
| New tank (first month or two) | About 5–6 hours | Plants are still settling and algae blooms are common; 2Hr Aquarist suggests starting short and increasing gradually |
| Low-tech planted (moss, ferns, Anubias, floaters) | About 6–8 hours | Easy shrimp plants grow in low light; 2Hr Aquarist gives 7–8 hours for stable low-tech tanks |
| No live plants | Short, regular day | Light mostly grows algae here; Aqueon gives about 8–10 hours for tanks without plants |
| Fighting algae | Cut back an hour or two | Change one thing at a time and give it a couple of weeks; see algae in a shrimp tank |
| Jar or Walstad-style tank | Longer, often about 12 hours | Plants do the filtering, so they need more light; see shrimp in a jar |
Whatever you pick, hold it for a few weeks before judging it. 2Hr Aquarist's advice is to choose one number and leave it alone for about four weeks, because a tank whose schedule changes every few days never settles.
Use a timer
A cheap plug-in timer or smart plug is the most useful lighting upgrade for a shrimp tank. Both sources above recommend one: a consistent day and night cycle is better for the animals and plants, and it stops the light being left on all night. Many LED lights now have a built-in timer or a ramp that fades the light up and down, which is easier on shy shrimp than a sudden switch. 2Hr Aquarist also advises against a "siesta" (lights off in the middle of the day) for plant growth; one continuous period is simpler.
If you want to see the tank in the evening, set the light period for when you are home, as Aqueon suggests. Shrimp don't care what time of day their light comes on, only that it is regular.
What kind of light?
- A basic aquarium LED is enough for the easy plants most shrimp keepers use. See best plants for a shrimp tank; mosses, Java fern, Anubias and floating plants all grow in low light without CO2.
- More brightness isn't better. 2Hr Aquarist points out that intensity and hours both drive algae, and that running a weak light longer doesn't make up for too little intensity for demanding plants. For shrimp tanks, a modest light on a moderate schedule is the usual goal.
- Color is mostly for you. The K rating on a light describes how the color looks to people, not how well it grows plants. Shrimp keepers often pick a light that shows off red or blue shrimp; that is a matter of taste. We haven't found good evidence that a particular light color is better for dwarf shrimp health.
- LEDs run cool. Aqueon notes LEDs don't heat the water the way older lights could, which matters in small tanks. If you use an old fluorescent or a desk lamp over a nano, check the temperature; see shrimp tank temperature.
Window sun and room light
Direct sun is the light to avoid. It adds hours you can't control, often grows green water or hair algae, and can heat a small tank quickly on a summer afternoon. Aqueon suggests placing tanks away from windows. If a tank must sit near one, block the direct sun with a curtain or a background and lean on the timer for the tank's day. Ordinary room light is fine; it just adds a little dim light around the edges of the tank's own schedule.
Light and shy shrimp
In a bare, brightly lit tank, shrimp tend to cluster in the few shaded spots, and that is often why owners see so few of them. Shade usually helps more than a dimmer light: floating plants, moss on wood and a few leaves give shrimp cover to graze in the open. A light that ramps up slowly, or a few minutes of room light before the tank light comes on, avoids startling the colony. See why are my shrimp hiding for other causes.
Common lighting mistakes
- Leaving the light on all day, or all night, without a timer.
- Putting the tank in a sunny window.
- Buying a strong planted-tank light for moss and ferns, then fighting algae.
- Changing the schedule every few days instead of waiting a few weeks.
- Blaming the light for every algae problem. Aqueon notes that nuisance algae is often driven by nutrients from overfeeding, skipped water changes or tap water, so check nitrate and feeding too.
Track it
Write your light hours on the free Maintenance Schedule printable alongside feeding and water changes. When algae or shy shrimp show up, you can see whether anything about the light changed before you start adjusting. Our shrimp tank maintenance schedule guide shows where lighting checks fit in a weekly routine.
Frequently asked questions
How many hours of light does a shrimp tank need?
Shrimp need only a regular day and night. Set the hours by your plants: often about 6 to 8 hours in a low-tech shrimp tank, shorter in a new tank or one with algae.
Do shrimp need light at night?
No. Turn the light off at night on a timer. Shrimp stay active in the dark and do not need a night light.
Can too much light hurt shrimp?
Light itself is rarely the problem, but long or bright light periods grow algae, and sun through a window can overheat a small tank. Bright, bare tanks also make shrimp shy.
Do I need a special light for a shrimp tank?
No. A basic aquarium LED on a timer is enough for the low-light plants most shrimp keepers use.
What color light is best for shrimp?
Color is mostly a matter of what looks good to you. We have not found good evidence that one light color is better for dwarf shrimp health.
Is sunlight good for a shrimp tank?
Direct sun is best avoided. It adds uncontrolled light, grows algae and can heat small tanks quickly. Indirect room light is fine.
Do I need a timer for my shrimp tank light?
It is the most useful lighting upgrade. A timer gives a consistent day and night, keeps the light from being left on overnight, and makes it easy to adjust the hours.
Sources: 2Hr Aquarist, How many hours of light does a planted tank need? (new tanks and algae 5–6 hours; stable low-tech 7–8; stable high-tech 8–9; beyond about 12 hours no gain; use a timer; hold a schedule for four weeks; no siesta; intensity and duration both drive algae; K rating is visual color); Aqueon, Choosing the right aquarium light (tropics about 12 hours of light; planted tanks 12 hours, unplanted 8–10 hours; use a timer; place away from windows; LEDs don't heat the water; algae often nutrient-driven); Shrimp Tank Hub's algae, plants, shrimp in a jar and hiding shrimp guides.