Brittle Star HELP?

[JJP161]

Ok last night all 3 of my brittle stars were just fine and ate small peice of shrimp. I did notice that one of the stars had lost part of it's leg. Today when I came home I found the same one with no legs and just his body with a couple of stubs. I thought he was dead, so when I tried to get him out he pulled himself under a rock. I do have a possible mantis shrimp. So what should I do and who did this? Thank-you

Joe

[Siberman]

Have you tested your water parameters lately?

[JJP161]

Sorry about that.

Ammonia 0
Nitrite 0
Nitrate <10
PH 8.4
SG 1.025
Temp. 75.4

[jenajet]

What other inhabitants do you have in the tank? The parameters seem just fine. Maybe provide a little more info, such as how you perform water changes, critters, things like that. How do the other stars look? How old is the system...anything you can think of even if it seems unimportant.

[Loverotties]

Yes the more info you give the better chance someone will know.

[JJP161]

I am brand new to saltwater and reef tanks. As for the tank it is a 75 gallon tank that has been up and running for 6 weeks.

150lbs live rock
75lbs live sand
30g sump with protein skimmer
60 blue leg hermits
35 astrea snails
3 brittle stars
1 slipper lobster
1 decorator crab
1 very small decorator crab
1 condy anemone
1 porcelin crab
4 cucumbers
2 clown fish
1 possible mantis shrimp - trying to catch and remove

1 "softball size" long tentacle anemone - has been MIA for 3 weeks
1 small mushroom frag - MIA for 3 weeks

Maint.
Replace evaporated water weekly with RO/DI water
10-15% water change every 2 weeks with "aged" RO/DI water

Brittle Star - Still alive and hiding under a rock

Thank-you
Joe

[DarthOcellaris]

first off, raise that temp up about 3 degrees

secondly, IME, brittle stars will start to fall apart like that and it's already too late I had one melt away for no aparant reason. I believe they are just like any other star: very sensitive to changes in the water.

[Loverotties]

I also think your tank is to new for Anemone.

[JJP161]

Please keep in mind I have kept African Cichlids for years but I am brand new to Saltwater, so I admit I know very little and I'm here to learn from you. The water temp of 75 degrees is what was recommended by Tampabay Saltwater and the book The Natural Reef Aquarium. The only filtration I have is my skimmer and the live rock and live sand. Using this "natural approach" I haven't seen any changes in water conditions except the nitrate levels dropping with each water change and then holding and since it is so new I have been testing the water every couple of days. The "condy" anemone and a couple curly cue anemones were hitchhikers with the live rock and have been doing very well but I will certainly wait to add more.

So as of now I should go ahead and remove the injured brittle star? Again thank-you everyone for all of your help.

Joe

[Siberman]

He's probably a goner but you might try putting him in quarantine. Check your test kits against someone else's if possible. I had a brittle do that but my water params were severely out of whack.

If you have a mantis he or a larger crab could be the culprit (not sure about the lobster).

[frankandmaura]

Starfish are very susceptible to fluctuations in salinity...if you are only topping off with new RO/DI only every week (which is what you said) you are probably experiencing a change in your salinity (few points at least).

How much do you add "weekly"?

[tdwyatt]

Originally Posted by JJP161

...running for 6 weeks.


Maint.
Replace evaporated water weekly with RO/DI water
10-15% water change every 2 weeks with "aged" RO/DI water

Brittle Star - Still alive and hiding under a rock

Thank-you
Joe

This represents a pretty wide swing in salinity, all week the salinity will be gradually increasing as water evaporates from the system, not such a big deal; but then going from a high salinity environment to a normo-salinity environment in a few minutes when you top off is quite stressful for echinoderms. Although the class Ophiuroidea sea stars are much more tolerant than the Asteroids or other classes of the phylum Echinodermata, these same wide swings can cause the damages you've described (many other Echinoderms that have evolved in full strength seawater would die under these circumstances). There is a reason that sea stars of the class Ophiuroidea are nicknamed "brittle" stars...


Get an auto-topoff device, not only will it stabilize your salinity swings, but it will make your life much easier. It would be smart to not get another echinoderm until you have installed an auto-topoff and you are confident that it is working correctly. Also smart to get and use a refractometer to measure your SG rather than swing arm hydrometer if that is what you're using to ealuate the SG of the tank's seawater.

A good chapter in a good book for you to read if you can find it , check with your local lipstick librarian for an ILL:

Austin, W. C. and M. G. Hadfield 1980. Ophiuroidea: the brittle stars. In Morris, R. H. D. P. Abbott, and E. C. Haderlie. 1980. Intertidal invertebrates of California. Stanford University Press. Stanford. Ca. pp. 146-159.


HTH

[Jnicho]

Originally Posted by frankandmaura

Starfish are very susceptible to fluctuations in salinity...if you are only topping off with new RO/DI only every week (which is what you said) you are probably experiencing a change in your salinity (few points at least).

How much do you add "weekly"?

Agreed...granted my tank is larger, but I evap at least a gallon a day...I would consider topping off every couple days to maintain SG.

[rhinokio]

i've had my tank going for months, but i've had no visible rise in salinity, and i've never topped with fresh water. i use a hydrometer and a refractometer to check it.

i do have a close lid tank, and a chiller so perhaps thats why i have such lil evap

[kwdelre]

Originally Posted by rhinokio

i've had my tank going for months, but i've had no visible rise in salinity, and i've never topped with fresh water. i use a hydrometer and a refractometer to check it.

i do have a close lid tank, and a chiller so perhaps thats why i have such lil evap

What kind of lights do you have?

That begs another question, which is hotter? PC or T5