The Harlequin Shrimp (Hymenocera picta) is a species of saltwater shrimp found at coral reefs in the tropical Indian and Pacific Oceans. They are found on rubble piles of coral reefs from Hawaii through the Indo-Pacific region. They can also be found around islands like the Galapagos or Gorgona that are bordered by coral reefs. They are rarely found below a depth of 30 meters.
Known also as Painted Shrimp, these crustaceans are part of the Palaemonidae family and are characterized by their carnivorous feeding habits.
Harlequin Shrimp have a beautiful and colorful pattern, which makes them one of the easiest shrimp to identify. They have a white or cream body that is covered with red and purple spots. They have ten legs, with flattened claws on the first pair of walking legs. The eyes are located on stalks, and the first pair of antennae on the head look like a flattened leaf. They are shaped like a praying mantis and have leaf-like appendages. For marine life, bright colors mean “danger.” The shrimp’s bright patches warn predators to stay away. The shrimp also has the ability to camouflage to appear as corals or sea plants.
As a general rule, Harlequin Shrimp grow up to two inches and weigh a few ounces. The female is slightly larger than the male.
The average lifespan of the Harlequin Shrimp is about seven years, although some hobbyists suggest about 2-3 years once introduced into a tank relating to some difficulty with their management.
The main difference between the male and female Harlequin Shrimp is that the female is larger. Females also have the colorful spots under their tails, whereas the males do not.
Harlequin Shrimp Care
The natural habitat for the Harlequin Shrimp is coral reefs in the Indian and Pacific Oceans.
The ideal habitat for the Harlequin Shrimp is a 10-gallon size saltwater tank. They can be kept in a reef tank because it does not hurt the coral, and they actually help the coral by eating parasitic Asterina starfish.
The suitable water temperature for the Harlequin Shrimp is between 72-84F/22.2-28.8C. The pH of the water should be 8.0 to 8.4, and the salinity should be 1.023-1.025. The tank should be well lit, and standard aquarium lighting is okay. Because they are sensitive to sudden environment changes, the water conditions need to be maintained. The water can be tested each week to ensure the water parameters are where they need to be.
The shrimp needs a cave to itself or for them and their mate. Plants, corals, and other decorations can be mixed in order to complete the tank setting.
Harlequin shrimp are weak swimmers and crawlers and can get sucked up into the filter and powerhead intake. These should be covered with a sponge. Strong currents from the filter or pump should be avoided as this can stress the shrimp and cause it to hide in its cave.
Because it does not eat the entire starfish and it is left to rot, a protein skimmer should be added to the tank so that the decaying starfish does not raise nitrate levels.
Diet and Feeding
The Harlequin Shrimp has a very specialized natural diet of starfish and sometimes sea urchins. Specifically, they like the tube feet of the starfish. When they find a starfish, they stand on it to immobilize it. Then, they flip it over to get to the tube feet. They drag it to their lair to eat it. The shrimp can often make one starfish last up to two weeks, sometimes bringing algae for the starfish to eat so it can preserve the starfish longer. Since they have hardy appetites and will only eat starfish, it is important to always have food available. Asterina starfish can be added to the tank. They are considered a pest species, but the Harlequin will eat them and keep them under control in the tank. They should be fed once a week, but they can survive for a few weeks without eating.
Harlequin Shrimp Breeding
Harlequin shrimp form breeding pairs and remain close to each other, both to reproduce and to have a hunting partner, in addition to deterring predators.
They pair up to increase the chance of producing offspring. The females mature quicker, becoming sexually mature after about seven months. Reproduction is sexual. Mating occurs about once a month after every molt. Approximately 1000 eggs can be fertilized at one time. After fertilization, they are moved to the female’s abdomen. Larvae emerge after 12-18 days. During the first few weeks, the larvae need small foods such as rotifer, brine shrimp eggs, and microalgae. The larvae go through 12 planktonic stages before the settlement stage at 5-6 weeks. At this point, they will eat starfish.
Because other fish will eat the larvae while they are small, a breeding tank shouldn’t contain any fish.
Although the male will mate with every female it comes across, it does have a preferred female to which it will regularly return.
These shrimp are territorial and will fight members of the same sex. Therefore, only one male and one female should be kept in the tank when trying to breed. Additionally, the environment must be ideal in order to stimulate spawning behavior. The aquarium should be clean, and the temperature should be kept at the higher end of their preferred range (82°F-89°F).
Harlequin Shrimp are good tankmates with smaller fish and some crabs. Because shrimp are territorial, care should be taken to avoid placing them in a tank with other shrimp as they will be aggressive. They will also show aggression within their species, and it is best to keep them alone or in a pair of one male and one female. In the tank setting, they will be picked on by any fish that eats shrimp, such as dwarf lionfish or hawkfish. Any large fish will also pose a threat.
Harlequin shrimp are mild tempered, peaceful, and shy. The shrimp will ignore other fish, hiding when they feel threatened. Starfish should not be placed in the same tank as a Harlequin Shrimp because that is their natural food, and they will eat them.
Because of their vibrant colors and their weak swimming abilities, it is hard for them to be inconspicuous. Therefore, they prefer to sleep during the day and feed at night to avoid larger, more active fish that could threaten them.
One thing to be aware of is that as the shrimp grows, it becomes too big for its shell. It undergoes molting, where it discards its shell and grows a bigger one.
Because they are territorial, only one Harlequin shrimp should be kept in the tank, or a pair of one female and one male. Both sexes show aggression toward members of the same sex. These shrimp will start fights with other species.
Avoid fish that commonly eat shrimp or are aggressive to shrimp. Crabs may be a threat to your shrimp, including Decorator Crabs, as they made overpower and eat the shrimp. However, smaller hermit crabs are good tankmates.
They do well with any fish that are reef safe or small enough not to eat it. Panda Gobies, Firefish, smaller Clownfish, and Cardinalfish are suitable tankmates.
WSSV, or White Spot Syndrome Virus, is a serious viral disease that affects cultured shrimp worldwide. It is a lethal virus that causes white spots in the exoskeleton under carapace. It can infect penaeid shrimp and other marine and freshwater crustaceans.
Harlequin Shrimp Price
Purchasing Harlequin Shrimp can be quite expensive. One shrimp can cost around $30, but prices could be higher. Larger shrimp may cost more. The cost of having to maintain a diet of starfish also increases the cost of care for the Harlequin Shrimp.
A quick online search brings up sites that sell these shrimp starting at $59.99 for a small shrimp.