[Calappidae]

When I was big on harlequin shrimp, I had an asterina population in a separate 30 gallon where the glass was completely covered, intentionally as a backup supply during the winter months where shipping starfish and driving on frozen roads wasn't an option. That system started out with about 50 additions and then kinda ignored it for the next 6 months.

One week of a bad freeze, I would throw 30 in a day. Long story short, that system of stars stopped existing that same week, these shrimp need a lot of them... figure harlequin shrimp only eat the tube feet part of a starfish (which on paper isn't a lot of the animal), then scale the difference between a chocolate chip and an asterina, its impossible to sustain harlequins on purely asterinas. Really think about how many tube feet there are on the leg of a starfish, and you can assume 1 asterina = 1 tube foot, then account for all 5 legs.

Harlequins are either a full commitment to buying the starfish (or rotation method), or a rented service that goes back where it came from when the job is done. Unless you have the literal ocean's worth of asterinas being given to you, its best to work with 1 medium chocolate chip star to last for 2 weeks, or 1 small for about a week, depending how fast or slow it dies, both in cost and results.