Sea cucumber in the aquarium

General information

Holothurians, commonly known as sea cucumbers, are invertebrates belonging to the echinoderm class, similar to starfish and sea urchins. They are characterized by an elongated, cylindrical body covered with small protuberances or spines that may serve a protective function. Their body is flexible, which allows them to change shape, aiding in hiding in rock crevices. The average length of most sea cucumber species ranges from 10–30 cm, and the diameter usually does not exceed 5 cm.
Sea cucumbers mainly inhabit fully saline seas (about 35 ppt), although some species have also adapted to less saline waters. Most of them live on the sea floor, often buried in sand or hidden in rock crevices and depressions, less frequently attached to the substrate. The most sea cucumbers are found in the tropical regions of the Indian and Pacific Oceans, especially in shallow waters, but they can also be encountered at depths up to 5000 meters.
One of the most unusual features of sea cucumbers is their ability to eviscerate, or expel parts of their digestive system in response to stress or threat. This action can deter predators, and the sea cucumber is capable of regenerating lost body parts within a few weeks. Additionally, some species secrete toxic substances as a form of protection.

Conditions for breeding

Sea cucumbers can be kept in reef aquariums. They require a large aquarium that provides plenty of open, sandy space for moving around in search of food. Optimal conditions include water temperatures ranging from 22 to 26°C, water hardness dKH 8-12, pH between 8.1 and 8.4, and salinity at 35 ppt. Sea cucumbers do not tolerate high levels of nitrates or copper-based medications. They should be kept with other peaceful aquarium inhabitants, as they are very sensitive to aggressive treatment.

Role in the marine aquarium

Holothurians are extremely valuable members of the so-called “clean-up crew” in marine aquariums. They are natural substrate filters, feeding on detritus, or dead organic matter, found in the sediment. Their feeding process involves sifting through sand and silt in search of food, which they then excrete, leaving clean sand behind. This helps maintain the cleanliness of the sand in the marine aquarium, which translates into water quality.

Adding a sea cucumber to the aquarium requires proper conditions. Above all, the aquarium must be well stabilized with an adequate amount of organic detritus, which is the main source of food for sea cucumbers. Fine sand as a substrate is preferred, as it allows for efficient feeding. It is also necessary to avoid overpopulating sea cucumbers in the aquarium to prevent competition for food.

Risks and challenges

Sea cucumbers require gentle handling during transport and introduction to the aquarium, as they are prone to stress, which can lead to evisceration or death. Additionally, some sea cucumber species may release toxins that are dangerous to other aquarium inhabitants in the event of injury or death.

Summary

Sea cucumbers are fascinating and useful additions to marine aquariums. Thanks to their role in cleaning the substrate and their unique features, they can enrich any marine aquarium, provided the right conditions are met for their life. Their presence not only helps maintain the cleanliness of the marine environment but also adds exotic charm to any aquarium.