[Richy]

Here's a coincidence..I had two clowns for about 6 months and just today the serpent starfish wrapped one of them up and was devouring him head first....when i got the clown out he was whole but dead...12 hours later the other clown is swimming upside down but he seemed to be fine today...is it coincidence that he has a bacteria or bladder problem on the same day the other clown died? also why did the serp want to eat the clown ...am i underfeeding him?

[Ninong]

Most seastars are ravenous omnivores. If they get big enough and hungry enough, they will eat just about anything they can capture.

Seastars in the genera Linckia and Fromia are reef-aquarium safe but they may not survive long term in captivity.

It is difficult to generalize about "serpent" stars or "brittle" stars because those terms have no real taxonomic significance. In the hobby we tend to refer to ophiuroids as serpent stars or brittle stars and to asteroids as seastars.

I have a nice reddish ophiuroid that I have had for some two years now without any problems but these things are unpredictable. I hesitate to try to identify mine but I believe it to be one of the relatively safe species. The one with the worst reputation is the Atlantic green brittle star (Ophiarachna incrassata). That one is definitely not a good choice in a reef aquarium or around small fish.

I have no idea why your second clownfish is swimming upside down but it's obviously not a good sign.