Harlequin shrimp are one of the most colorful shrimp species available for aquariums.
Unlike most shrimp, they are active during the day, making them entertaining to watch. They live best in pairs of one male and one female. Pairs mate for life, hunt together, and defend their home from predators.
Harlequin shrimp aren’t a good fit for most home aquariums despite their popularity. They are challenging to care for because they are very sensitive to water quality. Aquarists must keep pristine conditions for their shrimp to be healthy. They are also highly picky eaters that will starve to death if their owners don’t give them the right food.
Only expert saltwater aquarium keepers should attempt to take care of Harlequin shrimp. Prospective keepers should continue reading to see if they are the right fit.
For a concise care guide, check out the table provided below.
What Are Harlequin Shrimp?
Harlequin shrimp are vibrantly colorful shrimp with unique patterns and body shapes. They also go by the name “painted shrimp.”
Zig-zagging lines and spots stand out against their cream-colored bodies. They also have unusual, geometric-shaped bodies.
These shrimp live in the Indo-Pacific amongst the rubble of coral reefs. Their bright colors help them to blend in and prevent them from becoming a meal.
- Common Names: Harlequin Shrimp, Painted Shrimp, Blue Harlequin Shrimp
- Scientific Name: Hymenocera picta, Hymenocera elegans
- Origin: Tropical Indo-Pacific
- Length: Up to 2 inches
- Aquarium Size: 10+ gallons
- Temperament: Peaceful; Territorial toward their own species
- Ease of Care: Difficult
Harlequin Shrimp Care, In A Nutshell
Consult this Harlequin shrimp care sheet for quick care tips:
| Aquarium Size | 10+ gallons |
| Water Temperature | 72-82°F (22.2-27.8°C) |
| pH | 8.0-8.4 |
| Carbonate Hardness (KH) | 8-12 |
| Salinity | 1.023-1.025 |
| Safe Water Levels | Ammonia: 0 ppm Nitrites: 0 ppm Nitrates: <20 ppm |
| Decorations | CavesRocks Corals Plastic vegetation/other decorations |
| Tank Mates | Do best in pairs of the opposite sexSmall, reef-safe and shrimp-safe fishSmall, reef-safe and shrimp-safe inverts |
| Diet | Starfish Sea urchins (occasionally) |
How To Care For Harlequin Shrimp
Harlequin shrimp are extremely challenging to care for. They even present problems for those with previous shrimp-care experience.
Yet, they are one of the most colorful and entertaining shrimp to house. Raising Harlequin shrimp is a rewarding experience for those up to the task.
Tank Size
Being small animals, Harlequin shrimp don’t need much space. They can live in a species-only tank of 10 to 20 gallons.
It’s exceptionally more difficult to maintain nano saltwater tanks than freshwater tanks. The water parameters are more likely to fluctuate. Harlequins are very sensitive to fluctuations. A 20-gallon is preferable to a 10-gallon.
Many saltwater aquarists prefer to set up tanks larger than 20 gallons. Aquarists can stock these tanks with fish that are safe around Harlequin shrimp. Larger tanks are often more aesthetically pleasing and are easier to maintain.
Water Parameters
Harlequin shrimp have specific requirements for the water quality in their tank.
Due to their sensitivity, aquarists must ensure the water parameters remain stable.
For best results, keep the aquarium within these parameter ranges:
- pH: 8.0-8.4
- KH: 8-12
- Specific Gravity (Salinity): 1.023-1.025
- Ammonia: 0 ppm
- Nitrites: 0 ppm
- Nitrates: >10 ppm
Saltwater organisms tend to be more sensitive to water quality than freshwater organisms. Saltwater invertebrates are more sensitive to ammonia, nitrites, and nitrates than most fish. Harlequin shrimp are even more sensitive than most saltwater invertebrates.
Aquarists should try their hardest to keep their nitrates at 0 ppm. Nitrates should never exceed 10 ppm. Nitrites and ammonia should always be at 0 ppm. Anything higher than 0 ppm is likely to kill the shrimp.
Aquarists should only add these shrimp to established tanks. Never try to add Harlequin shrimp to a recently-cycled aquarium.
Filters
Don’t rely on filters to keep the aquarium clean; they won’t be enough for highly sensitive Harlequin shrimp.
Aquarists should also set up a refugium or protein skimmer.
Refugiums
Refugiums are small areas that share the same water as the main aquarium. They offer a controlled way to grow algae and microorganisms. Refugiums aim to replicate natural reef systems in the wild.
Those with a sump can dedicate a specific area of the sump to the refugium. Another option is to buy a pre-made refugium that hangs on the side of the main tank.
Sumps
A sump is an extra tank attached to the main aquarium to move water. Most aquarists place the sump in or behind their aquarium stand where viewers can’t see it. The sump moves water from the aquarium to the sump and vice versa.
A sump’s job is to keep the water clean. They increase the water volume, which helps keep the water parameters stable. They allow room for more filter media as well. The more filter media a sump has, the easier it is to control the water parameters.
Sumps are the ideal places to create a refugium.
Protein Skimmers
A protein skimmer is a piece of equipment that removes organic matter from the aquarium. It also provides extra oxygen.
Water Flow
Harlequin shrimp are weak swimmers and crawlers who don’t do well with a lot of water flow. Get an adjustable filter and keep the current low. Avoid powerheads that create a lot of currents.
These shrimp prefer to live amongst the coral rubble. They rarely climb on top of the corals themselves. Starfish, the shrimp’s prey, live in coral rubble. Ensure the filter’s flow points away from the coral rubble.
Directing the flow horizontally across the water’s surface is a good idea. Another option is using a spray bar that minimizes the force of the flow.
Since they are tiny, these shrimp easily get sucked into filters. Always cover intake valves with a sponge to prevent the shrimp from being sucked up.
Temperature
As a tropical species, Harlequin shrimp need water temperatures between 72-82°F (22.2-27.8°C).
Hobbyists should equip their tanks with a water heater, even if they live in a warm climate year-round. A good quality heater prevents temperature fluctuations, keeping the temperature stable.
Getting an adjustable heater to lower or raise the temperature when needed is best. Being able to change the temperature is especially helpful when the animals get sick.
Keep a thermometer in the tank and check the temperature every day. Even the best heaters can malfunction and cause temperature issues in the tank, though it’s rare. Catching these issues early can be the difference between life and death for the shrimp.
Decorations
Harlequin shrimp are fearful and elusive; they need lots of hiding places. Provide them with caves they can retreat to. They are more likely to be active in the open when they know they have caves nearby to hide in.
Tanks that are too bare will frighten harlequins. Rather than being active, they’ll find a place to hide wherever possible and seldom come out.
Often, a bonded pair will choose a cave and defend it together. They use the cave for eating and resting and drive off other shrimp or fish trying to enter.
After capturing a starfish to eat, the pair sometimes drags the organism back to their cave to eat.
Cleaning
The process of eating starfish is messy. Leftover decomposing bits can quickly raise the ammonia in the tank. Once the shrimp finish eating, remove the leftover starfish pieces with a net.
Aquarists must keep on top of water changes to keep the aquarium healthy.
Tank Mates
Harlequin shrimp are social animals that enjoy being in pairs. A pair of shrimp often work together to hunt their prey.
Pairs should comprise a male and a female. Harlequin shrimp are aggressive to members of their sex.
It can be tricky to sex these shrimp; do so with care.
Females are slightly larger and have spots under their tails. Males will not have any spots.
Harlequins are often kept in large groups in the pet store. Sometimes, individuals will form a bond during their time in these tanks. Aquarists can watch their interactions and sometimes pick out a mated pair.
Fish & Invertebrates
Harlequin shrimp are reef safe — one of the safest shrimp species for corals.
Harlequin shrimp only eat starfish and pose no threat to coral or anemones. They can live with any invertebrate that is “reef-safe,” save starfish.
Invertebrates safe with Harlequin shrimp include:
- Feather duster worms
- Corals
- Anemones
- Sponges
- Clams
- Other sessile (non-moving) invertebrates
- Green emerald crab (Mithrax sculptus)
- Small hermit crabs
- Scarlet cleaner shrimp
- Blood red fire shrimp
- Small snails
Aquarists shouldn’t keep Harlequins with any starfish or sea urchins they wish to keep alive.
Harlequin shrimp can live with any fish deemed “reef-safe.” Fish that are not reef-safe are sometimes okay. Ensure they are small enough that they can’t eat the Harlequins.
Small fish that are safe with Harlequin shrimp include:
- Basslets
- Gobies
- Firefish
- Cardinalfish
- True Percula clownfish (Amphiprion percula)
- Other small clownfish species
- Yellowtail blue damselfish (Chrysiptera parasema)
- Tangs
- Lawnmower blennies
- Vegetarian marine fish
Avoid fish that can grow large or have aggressive personalities:
- Large clownfish
- Large and/or aggressive damselfish
- Puffer fish
- Triggerfish
- Wrasses
- Lionfish
- Hawkfish
- Other invertebrate eaters
Avoid large or aggressive invertebrates, like crabs. Crabs are opportunistic predators.
Beneficial For The Reef — Controlling Invasive Starfish
Harlequin shrimp benefit reef systems by controlling invasive Asterina starfish populations. Asterina are tiny, rarely growing more than 1 in (2.54 cm) in diameter. Yet, they reproduce rapidly and can overrun a tank in a few weeks.
Asterina starfish reproduce by fission. They shed a leg or two and grow a whole new starfish from those legs.
Aquarists can not manually remove Asterina starfish because they might accidentally damage them. Damage only causes them to multiply.
While most Asterinas are harmless detritivores, some attack coral polyps. A cluster of Asterina starfish can devastate a coral reef system. It’s better not to take the chance when keeping a reef tank.
Harlequin shrimp eat Asterina starfish. They consume the whole body, leaving nothing for the starfish to regenerate.
Feeding
Feeding Harlequin shrimp is possibly the hardest part of caring for them. They live on highly specialized diets of starfish and, sometimes, sea urchins.
Unlike other saltwater species, aquarists can’t wean them onto other foods. Harlequins will starve to death if they don’t receive the right diet.
Fortunately, Harlequin shrimp will eat any starfish provided to them. Stick to medium-sized starfish, as they tend to be the easiest to eat.
Most starfish species common in aquariums work well. The chocolate chip starfish (Proteoreaster nodosus) is the cheapest option. Any starfish from the Linckia species also works nicely.
Harlequins don’t seem to like serpent starfish. They may eat them if there are no other options.
Feeding Asterina Starfish
Most Asterina starfish are harmless. Some hobbyists like to add the harmless kind to their aquariums. Doing so provides a nearly never-ending food source for Harlequin shrimp.
Still, a single Harlequin shrimp can eat up to 15 Asterinas a day. Hobbyists that don’t have enough Asterina to keep their Harlequins fed will need to buy starfish.
* Be careful not to choose the coral-eating Asterinas. *
How Do Harlequin Shrimp Eat Starfish?
To eat a starfish, a mating pair usually works together. First, they stand on the starfish to keep it from moving, then flip it on its back. Second, the shrimp often drag the starfish into their cave.
Eating a single starfish can take up to two weeks. Bringing their meal to their cave prevents other animals from preying on it.
Eating a starfish is a gruesome business. Harlequins keep the starfish alive while they eat it so it stays fresh.
The shrimp begin by feasting on the delicate tube feet — the appendages the starfish uses to move. Once those are gone, they make their way from the tips of their arms to the center of their body.
A starfish won’t die until the shrimp begin eating the central disk at the center of their body. They prefer their starfish fresh and won’t eat the central disk until they’ve eaten the rest of the body.
Some hobbyists have even reported their Harlequin shrimp feeding their starfish. They bring algae to the starfish and place it over their central disk for them to eat. Doing so keeps the starfish alive for the duration of the shrimp’s feeding process.
Breeding
Breeding Harlequin shrimp is challenging. Their water parameters must remain pristine.
They also need a steady source of food and an ideal mate.
Move the mother and father to a separate tank two to three days before the eggs hatch. Once the fry hatch, move the parents back to the main tank.
The fry tank should have no filter, as filters will suck up the juvenile shrimp.
Baby Harlequin shrimp hatch as larvae and remain in this phase for five to six weeks. After this time, the larvae settle to the bottom of the aquarium and turn into miniature shrimp.
Feed the shrimp fry planktonic organisms like green water algae and rotifers. Once they grow big enough, aquarists can transition them to brine shrimp nauplii.
Common Health Problems
There are no health problems specific to Harlequin shrimp. Still, they are prone to some health issues common in shrimp in general.
Molting Problems
One of the most common problems amongst shrimp is issues with molting.
A shrimp’s shell doesn’t grow with its body. As the shrimp grows, they must shed their old shell and regrow a new one that fits their larger size.
Shrimp may have trouble molting if they don’t receive enough calcium. They may also have molting issues if the water conditions are unsuitable.
The exoskeleton may not split right, causing the shrimp to have trouble crawling out. Shrimp that get stuck for too long may die.
The best way to prevent this is to ensure there is to keep the tank clean and provide calcium.
Infections
Harlequin shrimp are very sensitive to changes in water parameters. Changing water conditions cause stress, which lowers the shrimp’s immune system. As a result, they may develop bacterial, fungal, or parasitic infections.
Hobbyists must treat infections right away to prevent them from spreading.
* All invertebrates are sensitive to many medications used to treat fish. Always choose a medication that says it’s “invert-safe” or “reef-safe.” Avoid copper-based medications as they kill shrimp. *
FAQs
How Much Do Harlequin Shrimp Cost?
Harlequin shrimp are among the most expensive species, with a price tag between $40 and $200. The price depends on the size, species, and the number of shrimp the customer plans to buy. Buying these shrimp in pairs is often cheaper than buying two separately.
Can Harlequin Shrimp Eat “Toxic” Starfish?
Harlequin shrimp are not bothered by the toxins produced by some starfish.
Most starfish do not contain toxins. Hobbyists don’t need to worry about toxic starfish in their aquariums.
In the wild, a few starfish species have toxic chemicals in their body walls. These toxins are a defense mechanism against predators.
Harlequin shrimp are immune to these toxins, and some researchers think they may use them. These researchers hypothesize that Harlequins absorb the toxins. Then, they use them to keep predators away.
Why Do Harlequin Shrimp Most Often Die In Aquariums?
The most common causes of death for Harlequins are unfit water and starvation.
Harlequin shrimp are incredibly sensitive to changes in water parameters. Even small fluctuations can cause them stress and illness.
These shrimp are also very picky and only eat starfish. They may eat sea urchins if nothing else is available, though it’s rare.
Some aquarists assume they will eat other fish foods when they get hungry enough, but they won’t. It’s not possible to wean Harlequin shrimp onto other saltwater fish foods; they will starve.
