fish dieing..unknown reason

[rnscross]

My fish are currently in a hypo treatment (last spots seen on 21/8) however over the past week I have had fish go MIA and then turn up dead. Today I actually got to see what was happening. The appear to loose balance and swim up side down and before experiencing respirator distress. The only marks appear from them bouncing off rocks, no other outward signs of illness. All fish eat vigorously the day before/day of their death. The order of the casualties;
2 occie clowns
1 eiblii angel
1 coral beauty
1 majestic angel

Inhabitants left,
1 blue tang
1 tenneti tang
1 long nose hawkfish
2 fairy wrasse
1 linneatus wrasse
1 bangaii cardinal

Tank is 6x2x2
Water parameters
Salinity 1.008-9
Ammonia 0 api
nitrite 0 api
nitrate 10ppm api
pH 8.4 digital pen

I'm at my wits end as to what to do.

 

[namxas]

How accurate is your digital pH meter? One typically sees low pH values in a hypo tank.

Also, if the fish seem to be in respiratory distress, you should drop an airline into the tank.

Finally, do a WC.

We've had hypo "go south" for know apparent reason too, and the fish were clear of spots.

 

[Chris27]

Why are you doing a hypo treatment? As a treatment, it's really only useful for Crypt, and not very effective against other types of parasites / diseases. Perhaps you're dealing with something else such as Brook or a bacterial disease.

 

[SNAKEMANVET]

I agree with namxas, that ph drops low in hypo.Are you doing this in your display tank with live rock and sandbed.

 

[rnscross]

The hypo in the DT, however the rock wasnt that 'alive' outside of bacteria. I'm doing hypo as the fish had ich. The high pH had concerned me as well, but this is a tank with alot of calcium carbonate, so I thought that it might be buffering it up.

I'll recalibrate my pH pen, and do a 10% water change and hope that nothing else dies.

 

[SNAKEMANVET]

My fish are also in hypo in dt,the substrate should hold the ph steady.The only other thing I can think of is the salinity right.I double checked mine with lfs to make sure it was correct before dropping mine down 1.008.Other than that I have no idea.

 

[MrTuskfish]

An obvious question: You are using an accurately calibrated refractometer, right? There was a hobbyist a while back who lost most fish overnight in hypo, turns out he was using a swing arm hydrometer.

 

[rnscross]

So after checking my pH pen (it was calibrated correctly, compared it to a lab grade pH meter) I created a calibration fluid for my refractometer ( as suggested) as I have up until this point used RO to calibrate. I made up 1.025 solution (1.75g in 50mL dH2O) and the refractometer was out by 0.001 so that means that my fish were exposed to 1.007 salinity. From asking questions before starting I thought that this was acceptable. I've not had any more fish die in the past 5+ days. Everything has remained stable so I'm unsure as to what went on..

 

[sandwi54]

So after checking my pH pen (it was calibrated correctly, compared it to a lab grade pH meter) I created a calibration fluid for my refractometer ( as suggested) as I have up until this point used RO to calibrate. I made up 1.025 solution (1.75g in 50mL dH2O) and the refractometer was out by 0.001 so that means that my fish were exposed to 1.007 salinity. From asking questions before starting I thought that this was acceptable. I've not had any more fish die in the past 5+ days. Everything has remained stable so I'm unsure as to what went on..

1.007 is NOT acceptable! all the literatures say not to go below 1.008 and there's a reason for that. I read it in an article somewhere that the lowest salinity typical marine fish could handle is 1.008; has to do with something regarding their abilities to osmoregulate correctly. i can't remember the details but that's what I read.

I think you should bring the salinity back to 1.008 even though there were no more deaths.

 

[rnscross]

when I posted on here regarding my plan for the hypo, one person said that they had taken their tank to 1.007. If it was the fact that the salinity was too low, why did it kill the fish it did? rather that the whole tank, or the smallest or the biggest? it seems a random assortment.

I was also under the impression that fish had an internal "salinity" of aroun 1.006 and the reason you cant drop the external salinity any lower is that it will kill the fish through diffusion of all their ions into the water, as they only have the biomechanics to export excessive ions from their environment not retain them.

 

[sandwi54]

I don't know why it only killed certain fish, but each fish's individual tolerance varies. this applies to anything. some fish are more sensitive to copper, some are not. some have higher tolerance of ammonia/nitrite while others die quickly of presence of any. throughout the number of years i've come to realize that nothing can be generalized in this hobby and each fish is different. just because a fish is small it doesn't mean it's weaker than much larger fish.

you may be right about the 1.006. i'm not a marine biologist and i can't answer that question. i'd also think that all fish are different in terms of the lowest salinity they can handle, and maybe that's why all the literatures recommend 1.008 to provide some margin.

This being said, perhaps there's something else going on in your tank. at 1.007 it should be very difficult for the pH to stay as high as 8.4, even though there's a lot of live rocks. have you been dosing buffers or sodium carbonate/bicarbonate materials to drive up the pH? when I did hypo in my DT before (with about 200 lbs of live rocks), my pH would hover around 8.0-8.1 and I have to manually dose sodium bicarbonate to keep it from dropping below 8.0.

 

[MrTuskfish]

when I posted on here regarding my plan for the hypo, one person said that they had taken their tank to 1.007. If it was the fact that the salinity was too low, why did it kill the fish it did? rather that the whole tank, or the smallest or the biggest? it seems a random assortment.

I was also under the impression that fish had an internal "salinity" of aroun 1.006 and the reason you cant drop the external salinity any lower is that it will kill the fish through diffusion of all their ions into the water, as they only have the biomechanics to export excessive ions from their environment not retain them.

I would really hesitate to do something based on the experience of one voice on the forum. Like yours, his hydrometer could have been off too.IMO, any statements on this forum are simply opinions and experiences; nothing more and nothing less. When it comes to vital info, I really do serious research and then decide. You can find someone on this forum who claims to have done absolutely anything regarding this hobby you can think of; but that doesn't make it a universal fact. Also this hobby isn't filled with a lot of "absolutes", there are exceptions to just about everything and we need to go with the best decision we can. The selective deaths of some of your fish may (or may not) fall into this area.

 

[rnscross]

MrTuskfish I think you may have hit upon the an important fact that I overlooked. I did do some serious research before starting, but in all the publications that I read I couldn't find what the lowest tolerances were for the fish.

The tank seems to have stabilized now at 1.008, pH 8.1. I didnt add any buffers or anything, just a small 10% water change. All fish currently seem active and all have their appetites. I dont know what it was, but in future I think I will try to calibrate my test kits more frequently. Thank you all for the input.

 

[sandwi54]

1.008 and pH=8.1 sound like the right parameters. Good luck with the hypo and let us know the result!

 

[snorvich]

So after checking my pH pen (it was calibrated correctly, compared it to a lab grade pH meter) I created a calibration fluid for my refractometer ( as suggested) as I have up until this point used RO to calibrate. I made up 1.025 solution (1.75g in 50mL dH2O) and the refractometer was out by 0.001 so that means that my fish were exposed to 1.007 salinity. From asking questions before starting I thought that this was acceptable. I've not had any more fish die in the past 5+ days. Everything has remained stable so I'm unsure as to what went on..

I believe your SG error was the problem. Do NOT calibrate to RO water, best to use Pinpoint or some other standard that is at 1.0264

 

[rnscross]

is it ok to calibrate it to the 1.025 solution I made (its pretty accurate as I used a scale that read in mg to 1 dp. )?

 

[snorvich]

is it ok to calibrate it to the 1.025 solution I made (its pretty accurate as I used a scale that read in mg to 1 dp. )?

I personally would not. I only use Pinpoint solution.