Sea Cucumbers (Holothuria sp.) are sand sifting members of a reef tank Clean-Up Crew, but are not recommended for beginners as they can release toxins if they are stressed or injured that can potentially wipe out a tank. While they are known for their sand sifting abilities they are often visible on the surface. These Indo-Pacific natives can grow to nearly a foot in length, so make sure there is ample space for them in the tank; 30 gallons is the minimum recommended size. Certain species of Sea Cucumbers are able to reproduce both sexually and asexually so it is possible for population numbers to multiply with only a single individual. Their diet consists of detritus, and food waste they find when sifting through the sand bed. As these guys can nuke a tank, make sure to keep covers or shields on power heads, and intakes to reduce the chances of them getting stuck and killed. When it comes to water quality, they are sensitive, so make sure to slowly drip acclimate them. Additionally make sure to regularly test the water as they do not tolerate poor water quality or medications with copper.