Fish in danger from urchins?

[csababubbles]

I have a couple of long spined black sea urchins. Can I add them to my tank that holds large angels, butterfly, moorish idol, and large puffer, etc? There is lots of algae to eat for them but when I had them in my 45 gallon tank they were annoying for two reasons: knocking corals down as they walked around and one time my blenny got pricked by one and had a whole in his side that eventually healed.

So are my large fish in danger of being pricked? Will they die if pricked? Or just get hurt? Mostly scared for the panda puffer since he's got a large surface area for being pricked.

 

[csababubbles]

anyone ever keep these urchins? have they ever pricked your fish?

 

[DonW]

I had a 10" one and he never hurt a fish, just liked to eat sps. Was a pain in the rear. Dont know what would happen if a fish floated into one.

Don

 

[Sascha D]

Someone correct me if I'm wrong, but urchins cannot raise, lower or eject their spines. They're there purely for defensive purposes. Your fish would have to go after then and hurt themselves in the process.

I wouldn't add them for 2 reasons. You obviously really love your fish, some of them rare and expensive, and you never know what a fish is going to do. Also its a real PITA because they knock over stuff in the search for food. I wouldn't put them in a tank that didn't have solid rock structures; tied, pegged, puttied or glued together in some way.

Considered a linkia star or you just like the look of the urchin? Hopefully Lee will have better insight.

 

[csababubbles]

Whenever I put my hands within a foot or two of their spines, they always react by pointing a large part of their spines towards me. So if a fish swims by I could see the urchin pointing its spines towards it, defensive or not it stills looks painful to be blown into one or swim into one accidentally.

But I was not really concerned about my urchins aggressive attempts of impaling the fish, lol, but rather that the fish accidentally get nailed by one because even though the fish would easily avoid them in the wild, in the confines of a tank, they have less swim space around them thus accident seems inevitable.

So my main question is if a fish gets stung by a long spike, is it a real possibility it could be fatal?

 

[Sascha D]

Yes it could be fatal.

With any puncture there is a chance of infection. If it hits the liver, toxins will flood the bloodstream and your fish will be dead by the end of the day. If its hits the swim bladder, your fish could live a few days but swim bladder damage will not heal.

Because your fish are large, if they are pierced then they will likely break the spine and possibly leave a pice inside the wound. If pierced near the mouth or gills it could cause swelling and prevent feeding.

 

[Maxx]

I have a diadema urchin that I've kept in my 120 for several years now. 2 years ago my Tomini tang got zapped by the urchin, or crashed into it face first. There were several pale white circles surrounding the black spines in the center wound. The fish recovered just fine with in a day with no ill effects.

I say go for it.

Nick

 

[dnjan]

I have had long-sine urchins in my tank for years. Never had a problem with fish getting hurt on them.
The problem I have is that one of my two urchins scratches the acrylic tank with its teeth, and I have to periodically buff out the scratches.

 

[luke33]

Problem i see is the puffer going after it.

 

[csababubbles]

yea i figured he might be inclined to go after the urchin but if he did i could just yank them out. watch, i bet you he will ignore them when i'm there and as soon as i go to bed hes going to enjoy himself a nice midnight snack.

 

[luke33]

lol, maybe! I would imagine he'll give him a bit or two, hopefully he won't like the taste. My DFP tasted everything when i had him. Even a nice chunk of my forearm.

 

[Maxx]

What kind of puffer is it? If its of the arothron species, (not spiny) then I wouldnt think it would try more than once or twice depending on how big the puffer is in relation to the urchin.

Nick

 

[Sascha D]

I have had long-sine urchins in my tank for years. Never had a problem with fish getting hurt on them.
The problem I have is that one of my two urchins scratches the acrylic tank with its teeth, and I have to periodically buff out the scratches.

Man I had never thought about the scratches! I just thought it was me being an idiot hehe. I guess I just never thought about it

 

[rlugo29]

I had a 10" one and he never hurt a fish, just liked to eat sps. Was a pain in the rear. Dont know what would happen if a fish floated into one.

Don

I thought long spines only eat algae? I've never read about them eating SPS

 

[Maxx]

Diadema and other urchins will occassionally graze on corals. If small frags are what they "chew" on, you can get some significant damage. If not, its generally not a big deal. I had one tiny frag that got chewed on pretty bad, so I moved it to another tank for awhile and it recovered nicely with no issues. Its back in the tank with the urchin right now without any incidents.

I suspect that the reason behind the "chewing" is nutrient deficiency. I know that when didema urchins are deficient in magnesium, their spines will turn white. Adding magnesium to the water will resolve that issue.

Nick

 

[rlugo29]

I know that when didema urchins are deficient in magnesium, their spines will turn white. Adding magnesium to the water will resolve that issue.

Nick

How about that. Cheap mag monitors.

 

[dnjan]

Man I had never thought about the scratches! I just thought it was me being an idiot hehe. I guess I just never thought about it

Lots of short (less than 1/8") scratches that eventually make it look a bit cloudy trying to see throuth the side of the tank. Fortunately, the urchins can't get all the way to the corners or the bottom, so polishing out the scratches isn't that difficult. Just need to find a time when I have the time, and the urchins aren't on the side I want to polish.
BTW - polishing out the urchin scratches also gets rid of the corraline that I haven't been diligent enough about scraping off the sides ...