The Harlequin shrimp originates from the island Sulawesi in Indonesia where it is collected from a number of freshwater lakes. It lives in freshwater sponges which it cleans by eating debris and algae from the surface of the sponge. This feeding behaviour has earned them their scientific name Caridina spongicola. The Harlequin shrimp does not require sponges to survive and can be fed a wide variety of food in captivity and be kept in a number of different setups.

The harlequin shrimp is a somewhat sensitive shrimp that is hard to keep and it is not recommended for beginners who want to keep their first shrimps. It is normal for this species to loose its colours when introduced to a new aquarium. The colour returns once it starts feeling safe in its new environment, and it is very important to decorate your aquarium in a way that makes the shrimp feel safe with a lot of hiding places. Despite a good setup with a lot of hiding places these shrimps are usually very shy during the first days in a new home.

The best setup for a Harlequin shrimp is one that mimics those Sulawesi lakes from which it originates. The pH-value should preferably be alkaline even though this species can adapt to neutral water or even slightly acidic conditions. The temperature should always be kept above 78 °F / 25.5 °C and an even higher water temperature near 85 °F /29 °C is better. The harlequin shrimp needs good water quality and is very sensitive to nitrogenous waste. If water quality drops it is best not to feed the shrimp for a few days. They will tolerate that better than a prolonged drop in water quality. Harlequin shrimps can be sensitive to rapid changes in the water parameters and large water changes are therefore not recommended. It is better to change a little water often.

Harlequin shrimps are easy to feed and will accept most types of commercial fish food. In the wild they do as earlier mentioned live on sponges where they eat a lot of algae. It is therefore recommended to use an algae based food as the base of their diet. They should however be offered a varied diet that includes occasional meaty treats. They are small shrimps and need to be fed small food. It is best to feed your harlequin shrimps after dark and they should not be fed more then they consume in2-3 hours.

As far as we know it isn’t possible to sex Harlequin shrimps based on external dissimilarities. It is possible that the females are larger but this notion has not been confirmed. The small size of this shrimp makes finding external methods of sexing harder than in other, larger shrimps.

The Harlequin shrimp is hard to breed but will breed in aquariums if kept in ideal conditions. Their reproduction rate is low and they usually only produce 10-15 eggs at a time. The eggs are carried by the female until they hatch after 20-30 days. The baby shrimplets look exactly like their parents with the harlequin pattern. The colour is however less intense in the fry.