Hello and wondering why crabs die

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KurtsReef

Aquarium Advice Regular
Joined
Oct 23, 2006
Messages
62
Location
North Boston, New York
First time visiting this forum, I did a quick search and did not find anything so a little background...

I have a saltwater tank that has been up and running for about 5-6 years, it started in a 45 Gal tank and was moved to a 75 gallon main and 30 gallon sump two years ago. I have lost a total of 5 fish over that time, however 3 of them were during a recent power outage which the water temp dropped to about 55F the others were presumably due to reasons other than water conditions. Two fish in the tank (Sailfin Tang and Maroon Clown) have been in the setup the entire time.

Corals also thrive, with the exception of (1) colony of xenia and (1) colony of candy cane coral it lives, grows, and propagates without issue.

I have (4) 96w power compact lights on the system, another small light in the sump to grow algae. There is a Prism skimmer in the sump, other than that the only filtration is liverock.

Now for some admissions...I do not believe in testing the water every day and making water changes as often as the aquarium industry states. The system has had only two real water changes and one of those was the switch from 45gal to 100gal system. I have had my water tested at the local store several times and they always give it a clean bill of health (I did test it almost daily the first couple months and have the kit not sure if the chemicals would be any good). I do not overfeed and my little eco-system seems to run perfectly well with one exception...the crabs do not live very long. The only crab that has lived for an extended time is a horseshoe crab that has not been seen since the power outage.

So, what are some things that would cause this? I am expecting the crabs to live off of algae mostly and do not give much food...am I starving them? That is my number one concern, as I cannot think of anything else that would be causing this anomaly of death in the tank.
 
My thoughts on water changes and why we do them. We do them to dilute the pollution....but we also do them to replenish nutrients that get used up. These are not things we commonly test for, so therefore all the testing you do/do not do, will not tell you what needs replacing and when, so we do it to cover the bases.

That being said, IMO, you are not covering your bases. It is IMPOSSIBLE to say what is killing your crabs if you do not test water regularly to know when things change. I am not criticizing your husbandry, I am just pointing out what to me, is the obvious, I don't think we can help you.

If you think they are starving, then feed them. That is my only suggestion if you arent going to test water or do water changes.
 
if you are not doing PWC you are probably not renewing some trace element that the crabs need...

and if you are not testing your water, then you may be having some spikes, Ammonia, PH... and not even knowing it.

if i was you i would go out and buy a NEW test kit and post the results, then start testing at least once a week, but also if you have something die or act funny. I would also start on Weekly PWC. there is a good chance that these thing might just solve your problem.

if it means buying in to (some of) what the big bad aquarium industry suggests, then for the sake of you fish and critters you might have to suck it up and do it! LOL

my 2 cents!
 
I agree with the rest. I had the same problem with my shrimp dieing, for "no apparent reasons". This just came up the other day, again. I believe my shrimp were dieing, due to the time between my PWCs. I tend to think, they would molt and use up the trace elements in the water, once those were gone, they could not grow or get the nutrience they needed. Once I set up my new tank, I plan on doing an experiment, to see how much iodine/iodide they use up out of the water.
What kind of crab was it?

WELCOME TO AA!!!
 
Sorry, I should have added that tidbit of information...I do replace the trace elements especially the iodine that is needed for them to be able to molt and/or change out shells.

I also neglected to mention the same is true of my shrimp, however they are normally found being consumed by a starfish or torn to bits by the tang whereas the crabs (several different species I have tried) presumably have decent defenses against the predators and hide in the rockwork pretty good.

I would think that if it were a toxin in the tank that the fish would be effected, and if it were a trace element the corals would be effective.

I appreciate the discussion and I am fully aware the masses believe in the water change routine, although most I know who perform them have nothing but problems by trying to micro manage every parameter of their tank.

Now along the lines of what Roka mentions, is there a test for iodine? I would like to test for trace elements perhaps I was not adding enough.
 
KurtsReef said:
Now along the lines of what Roka mentions, is there a test for iodine? I would like to test for trace elements perhaps I was not adding enough.
I was actually looking at this particular product, found on drsfosterand smith.com:
http://www.drsfostersmith.com/produ...&Ntx=mode+matchallpartial&Np=1&pc=1&N=0&Nty=1
I was also stumped at the deaths becasue my urchins did not have any problems. I tend to think of them as being less hardy than shrimp.
One more thing, I wouldn't recommend dosing a tank without the proper tests.
On PWCs, not trying to preach, but my 1st one was a MESS and took forever. Now, it only takes me about 20 mins to do one, with my premixed water.
 
KurtsReef said:
I appreciate the discussion and I am fully aware the masses believe in the water change routine, although most I know who perform them have nothing but problems by trying to micro manage every parameter of their tank.

This is a ridiculous statement. I do PWC`s every week and I`ll match mine or any of the others on this site that do PWC`s against your tank anyday. PWC`s are good for your tank as others have stated.
 
There are something like 40 other trace elements in the saltwater that we mix up, that the fish and inverts consume. Iodine is not the only one. I would have to agree with the rest that the reason you are losing your inverts is either from lack of trace elements or high levels of nitrate, which are taken out with water changes. I do a water change about twice a month, and really don't believe in adding in the other stuff that you are talking about "the aquarium industry" reccomending. It's actually rather simple to spend 15 or 20 minutes every 2 weeks doing a water change. If it could save my inverts, I know I'd make the effort.
 
melosu58 said:
KurtsReef said:
I appreciate the discussion and I am fully aware the masses believe in the water change routine, although most I know who perform them have nothing but problems by trying to micro manage every parameter of their tank.

This is a ridiculous statement. I do PWC`s every week and I`ll match mine or any of the others on this site that do PWC`s against your tank anyday. PWC`s are good for your tank as others have stated.

Thats a fine opinion to have, however with the exception of crabs not surviving my tank runs perfectly. I get some green algae that is not wanted, but that is one of the reasons it would be nice to have them survive. Feel free to "match your tank" thats not the point of the discussion and I did not state the system of PWC's did not work simply it is not a system I use and do not understand why people jump up with hostile attitudes when someone holds an opinion differing from their own. Others I work with who do routine changes have issues constantly, am I aware of the exact cycle they run? No, however I don't care too either its their system. I have spoken with others, like yourself who swear by them and if you find them working for you thats great continue on with them.

Jarred Darque said:
Do we know each other?
Im not sure Jarred, I live in North Boston, New York ...not to be confused with boston mass. Most other forums I belong to are photography in nature.

Devilishturtles, I would have to go in the other room to get the exact additives that I do use however they are supposed to contain all the trace elements. Iodine is simply one of two that I routinely add separately the other being calcium. Perhaps doing the water changes in lieu of the additives may be the final answer, I will have to check the ingredients of the salt vs what the additives have perhaps its as simple as my not giving them another element which they need. One of the problems I have with doing water changes is not trusting the city water, getting 10 gallons of water every couple weeks to use in the change was a big hassle and after reading up on some alternatives started to try this way.

Roka, thanks for the link I will be looking for some other trace element testing supplies as well. Need to stop at the local shop tomorrow.

JDogg, I did not mean it to sound that way "big bad industry" there is more than one thought on how to run a system. I have chosen my route, and find it to work fine for me with this one exception. If I can figure out what the problem is and fix it that would just make watching the aquarium that much more enjoyable. I stopped buying crabs about 2 years ago since it was basically a death sentence introducing them into the system.

BTW right now I am just watching everything hoping that it recoups from the power outage. I think the loss of life has ended and everything seems all that lived have become stable.
 
One of the problems I have with doing water changes is not trusting the city water, getting 10 gallons of water every couple weeks to use in the change was a big hassle

an ro/di unit would solve your problems then for sure.
 
Cool, keep us posted! I also ordered the Iodidine/dide test kit. So we might be able to compare notes.
 
OK, decided to try some things over the past few months and here is what I have done/seen.

The only thing I changed at first was to start performing 10-20% water changes once per week. I still simply used water out of the tap, bought a few crabs...they were dead within a week.

I then started to used filtered water along with performing the water changes. I performed a 25% change each week for 3 weeks and then bought more crabs continuing with filtered water changes at a rate of 10-20% each week...crabs lived.

Hypothesis at this point is the filtered water is he main problem.

The crabs have now been alive for about 3 months, that is a record for me with crabs. I perform water changes about 3 times per month now and still add calcium and iodine, still do not test for them.

I did place an order today for some test kits, more crabs/shrimp and even some live rock for them to hide in since I now also own a puffer.

Bottom line, I think it had more to do with the heavy metals in my water than it did with performing water changes and I also think performing the water changes is helping me to keep the right levels of iodine etc (Other things that I was not adding) in the water for them.

So, had to remember this sites URL so I could come give an update...perhaps I need to drop in more often.

Is there such a thing as too much live rock? I ordered another 45lbs today and think that will bring the total up to around 145lbs for a total approximate 100 gallon system. I have rock in both the main and sump now totaling about 100lbs.
 
I have been told 1.5 - 2.0 lbs of LR per gallon is whats recomended so you are good to go with 145lbs I would assume....
 
It should add some hiding places for shrimp and crabs...now that they live in the tank.

I assume the heavy metals in unfiltered or "City" water are what killed them, but will continue with the water changes on the possibility some trace elements were missing as well...but the change in process that occurred just prior to them living for extended time was the change from using city water to filtered water.
 
I have been told that there is over 89 different salts or trace elements in marine salt mixes. As Lisa stated long ago these are not tested for because they are in such small amounts but are very needed. That is my reason for PWC`s as well as lowering excessive nutrients. I`m glad your crabs are doing better.
 
Thanks, and that is why I will continue with them...did one today, changed out 25 Gallon.

I do not mind admitting when I am wrong, something either in the salt or that was in the non-RO water damaged the crabs/shrimp and nothing else in the tank. Now they live, so better to keep it up.
 
It wasn't brought up (and I'm kind of shocked) but how were you acclimating your crabs, which species of crabs where they, & what was the time period before death?

I have to agree on the whole ro/di filter and frequent small pwc myself since I've always had good success using both practices and am glad your crabs are doing well.

KurtsReef said:
I perform water changes about 3 times per month now and still add calcium and iodine, still do not test for them.
Extremely risky adding without testing of either of these!!! Excess ca will mostly hurt your corals and the pwc should keep it at 400 ppm or at the very most only need very minor dosing. It can also play havoc with your ph/alk levels.

Read Chemistry and the Aquarium: Calcium & Solving Calcium and Alkalinity Problems

Excessive iodine is toxic to your stock and in particular will most harm your crabs you are striving so hard to keep alive. Read this article for more info.
 
I have always been pretty careful with aclimation. The bags will generally float anywhere from 1/2 hour to 2 hours before I open them and begin to let a bit of water in every so often until the bag is full then releasing them. Prior to the past couple months where there have been no (Or very few, don't have a way of actually counting every little crab) deaths the crabs would live for a week or so before perishing, some up to a month. Crab species attempted were many...

I think the longest living back then were the emerald crabs, which I can remember one living until he molted twice before perishing whcih I think was about 2 months. He was the one exception. Have had pom pom, scarlet, red and blue leg, arrow, and several kinds of shrimp.

I should have added that I plan on testing, in fact the ph/alk and ca tests are on my front door step right now along with several others. They were ordered at the same time as some live rock. I was not planning on never testing.

Thanks for the link, will read up. I thought the ca was suppposed to be above 450 or above for optimal coral growth. The amounts of additional contents that have been going in were minor, but better safe than sorry.
 
Floating up to 1/2-2 hours gets the temperature correct but how long did you add water to the bags before turning them loose? Ever try the drip method? Inverts are very susceptible to rapid changes in ph/sg and dieing within a week or so often is the result of osmotic shock.

Mixing various species of crabs in a 75 gal is pretty tight living quarters, could the other crabs have taken advantage of another after a molt when it's most vulnerable?

NSW (Natural Sea Water) CA level is 410-420 ppm and increasing slightly to 450 ppm at most will help some corals thrive but really as long as it's between 360-450 ppm you're doing fine. At 450+ it isn't helpful and is a waste of ca additive which will typically precipitate anyways.

Checkout Reef Aquarium Water Parameters.
 
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