Originally posted by PuffrBware
Brittles are very aggresive
What do you base this on??
This is really just not true. But any animal that is left to scavenge will not pass up a free meal when it is hungry. And most brittlestars are left to scavenge.
Now I am biased towards brittlestars and am sworn to defend them, but really they are very cool and do not deserve something like that description.
The green brittlestar is a known predator, but I reckon that considering the number of people that keep them, very few have any issues. I had 3 in a 15g with a sixline wrasse and they never touched him. Ditto with many other species. But similarly, many people have issues with species other than the green...I would just say it is quite rare relative to the number of people who keep them. And it certainly is not a generalization.
Some people have issues which means some individual brittlestars may eat things...but by no means are they "very aggressive." It is a risk, in keeping a tank, that our animals might eat each other.
The brittlestar will not eat the eel. We are talking, at most, about very small fish like clowns or shrimp. But also note that many are "caught in the act" so people think...they are part of the clean up crew. I do wonder how many times they actually caught a fish versus how many times they were accused of it simply by doing their job and cleaning a dead one.
Brittlestars should not be left to scavenge and should be spot fed. They are not sand sifters. They will not generally harm sea cucumbers (again, I've kept them together). There is NO REASON they can not be kept together, IMO.
As for the cukes, well, be sure you actually get a sand sifter cuke and that you do not have crushed coral. You need a fine particle size for them to eat properly. It should be noted that sand sifter cukes may fair better in tanks than filter feeders, assuming again you have proper substrate for it. Bright colored cukes are generally not sand sifters.
Avoid sand sifter stars, which tend to starve in most tanks after eating good things (eg worms) in your sand bed.