From Aquarium Life;
"The best way to avoid problems is to place any Euphyllia corals out of contact range with any other corals. However, it has been reported that Euphyllia corals (with the exception of E. glabrascen) may be placed near each other, as they do not seem to have any negative interactions between species."
And from Dr. Ron Shimek
"Physical Attack
Other corals compete without chemicals, or utilize additional means of killing their potential competitors. In aquaria, probably the most important of these means are specially developed structures, called "sweeper" tentacles, used in an aggressive manner by many corals such as Galaxea and Euphyllia. Some anemones also utilize similar tentacles (Richardson, et al., 1979; Williams, R. B. 1991; Hidaka et al. 1997; Langmead and Chadwick-Furman. 1999a,b). About twenty or so years ago, the role of these tentacles as aggressive structures had not been elucidated, and they were often presumed to be functional as a means of getting extra food. If you take the time to do some reading in the older sea anemone and coral scientific literature, you may come across the term of "catch tentacle" used to describe these structures as they were thought to serve some special function in "catching" food. Well… they don't catch food, they are used to kill offending encroachers on the space of the coral or anemone, and they can do a pretty good job of it. These specialized tentacles contain a more potent armament of nematocysts, both in types and numbers than do regular tentacles. What I think is interesting about such tentacles is their absolute, and large, size. In many Euphyllia these tentacles may reach 12 to 15 inches in length, and they are more-or-less transitory. The animal will extend them out at will, and this may not be when the hobbyist is watching their tanks. The first time such structures are seen, it may be both enlightening and frightening. "
