Linckia and Fromia stars are some of the most delicate in the hobby and typically die from acclimation stress. Both require acclimations on the order of 4-8hours. They also both have similar diets, and tend to starve to death over a period of a few months to a year. Many Fromia especially seem to do well up to the one year mark and then die.
They are both algal and bacterial film grazers, and that includes other encrusting animals like sponges and bryozoans. This is their assumed diet...it may, in reality, be more specific. The diet available in our tanks may not be sufficient, or natural, if (for example) you keep a Caribbean blue Linckia in a tank full of Fiji LR.
They can not typically be spot fed, and no one should count on this. In order to keep them long term (many many years), you need a large mature tank, with a lot of LR. These species are not found in high densities in the wild, and should not be kept in high densities in tanks. Best success is with a single specimen (of either, not both, or any other similar star) in tanks up to 100g with 100lb LR. Larger systems may be able to keep more, but it is impossible to know until it is too late. IMO, a 75g with that much LR is the minimum tank size for a Linckia. Because of their smaller size, Fromia may be put in a smaller system (55g?) again assuming a lot of LR and that the system is at least 6 months old.
Imagine for a moment how much you must consume if you are eating algal and bacterial films. You require a great deal of it, and any competitors would mean you get less. Restricted space means you keep passing over the same spot, and the organisms that compose the diet do not have time to establish themselves again.
These stars are very delicate, and care should be taken to put them into the appropriate tanks. A few months or even a year is not considered success. In a proper tank, with constant water params (SG= 1.025, no AMM, Nitrite, Nitrate, constant Alk and pH, etc) and enough food without competitors, blue Linckia are known to reproduce. This occurs through arm drops, so not a large number of offspring are produced. This should be the ultimate judge of whether the system is sufficient and the star is doing well. Of course, it simply creates additional competitors, so some offspring may need to be traded in.
