Hyposalinity - What am I doing wrong?

[Brisbane Lion]

My son has been attempting to run his fish only tank through a course of Hyposalinity. To be on the safe side he reduced the salt level to 1.009 over a period of about a week (much longer than recommended). However he has lost a number of fish during the process. A yellow tang, an emporer, a flame angel to name just a few. Symptoms include bulging stomach, cloudy eyes and an appearance of peeling. A clown fish even jumped out. Can someone please help or advise?

Regards

[Puffer Queen]

Is there live rock or substrate in this tank?

What are the current tank parameters?

What are you using to measure the salinity?

[JHemdal]

The bulging abdomen on some/all fish could point to ascites - fluid build-up due to the kidneys not being able to deal with the lower specific gravity. I think the third question in the previous post is key - the specific gravity of 1.009, if measured improperly, could mean that the actual S.G. is even lower.

I'm concerned that so many people here are targetting a specific gravity of 1.009 to treat Cryptocaryon. I'm not fond of hyposalinity under the best of circumstances, but this value is lower than I am comfortable with. When I do use hypo, I target a specific gravity of 1.012 to 1.014

Remember, you can always drop the specific gravity fairly quickly, but be certain to go SLOW when you raise it back up.


Jay

[LisaD]

Have you checked water parameters? It is possible the hypo has killed of bacteria or small organisms in the tank, causing a crash. Check ammonia and nitrites asap.

[Brisbane Lion]

Ok thanks to all replies.......There is both a substrate live rock. I have read here that live rock is ok. Tank parameters are all good. No sign of any spiking and PH has remained stable. He ie measuring the salt with a refractometer and confirming with one of those plastic jobs with the swinging arm. Sorry...can't remeber what its called. Also he never quite got down to 1.009 The closest he got was about 1.012 but probs started registering once it got below about 1.016. It has now wiped out all fish except for a green wrasse which seems virtually unscathed and a clown fish which is looking decidedly ill.

[Freed]

Hypo is normally performed for no less than 4-6 weeks minimum. AND why are you checking the accuracy of the refractometer WITH the swing arm? The swing arm should be thrown away and the refracto should be properly calibrated with a known salinity solution.

[Puffer Queen]

Hyposalinity will kill off the microfauna in the live rock and substrate leading to a direct hit on the biological filtration as well as water parameter instability.

[NirvanaFan]

have nitrate, nitrite, and ammonia been tested for? What is your temp at? How long are you leaving the fish in hypo? Are you loosing them mid-hypo or when you are raising the salinity up? What size tank do you have them in? Are they stressing/chasing each other around in QT?

Whenever I have done hypo I got the salinity down to 1.009 over the course of 5 days. I usually do a 5 gallon water change every other day or so to keep all levels at 0. Ammonia and nitrite are what you really have to worry about. I would also make sure that your refractometer is properly calibrated. This is extremely crucial. After 4 weeks of the last sign of ick, I take a week to raise the salinity up to normal levels.

[stingythingy45]

You don't have to worry about Nitrite.
It's harmless to marine fishes.
Ammonia poisoning would be the highest priority.
But this would not cause bloating as far as I know.
Just clamped fins and rapid breathing,then death.

[LisaD]

You don't have to worry about Nitrite.

I strongly disagree. you DO have to worry about nitrITE. it is toxic to fish, but not so much as ammonia.

some people don't worry about nitrATEs, but some fish are sensitive to these as well. I have several species of fish that do very poorly when nitrate levels are elevated above 20-30 ppm.

most likely, if the biofilter has been affected by the hypo, you will see an increase in ammonia, which is the most toxic.

detectable ammonia or nitrITE are not acceptable water parameters.

"bulging stomach, cloudy eyes and an appearance of peeling" could be caused by a secondary bacterial infection, after parasite infection or stress from ammonia poisoning. a fish jumping out (the clown) could be indicative of distress from ammonia burn.

you really need to test your water to get an idea of what might be going on.

if you have other fish living, I suggest:

1) establishing a treatment tank asap

2) maintaining the best water quality possible, with frequent partial water changes of pH, temperature and sg matched, aged salt water (mix up a lot and keep it circulating).

3) medication, probably broad spectrum antibiotic for infection. determine whether additional treatment is needed for parasites.

[stingythingy45]

Funny,I've read where Nitite is not toxic to marine fish.
Fish can survive well over 300 ppm. of nitite.

[Freed]

I think you may have read incorrectly. Nitrite is the deadly one IIRC.

[LisaD]

you are thinking of nitrate. this is the third product of the nitrogen cycle: ammonia > nitrITE > nitrATE. nitrate is equivalent to what we use as fertilizer, which is why refugia with macroalgae is a good way to reduce nitrates. the plants use it to grow, depleting nitrate levels in the tank. when the macroalgae is pruned (removed from the tank) you are exporting the nutrient nitrate.

a regular schedule of water changes, avoiding overfeeding and avoiding overstocking are how most people control nitrates.

some fish can tolerate high levels of nitrates, but it really isn't good for them, and it is toxic to some species with high sensitivity.

here is a link to a short article that explains it:

http://saltaquarium.about.com/od/nit...atecontrol.htm

in fish only systems, some nitrates are acceptable, but nothing like 300 ppm. in FOWLR, you should be shooting for 40 ppm or less, emphasis on less. if I don't keep mine below 20 ppm, my seahorses, puffer and angler (all in different tanks, BTW) definitely show signs of distress.

[stingythingy45]

Nope......Nitrites.
Here's a link.

http://www.reefkeeping.com/issues/20...hf/index.php#6

I had a conversation with Randy about this earlier this week.
Had some questions concerning a nitrite level in an uncycled QT tank.

[LisaD]

you're right, I missed that article. honestly, that's the first I've heard that. however, all my experience with nitrite toxicity has been with freshwater fish, and I have always assumed it is equally bad for salt water.

still, guess I'm old school. I still think nitrites are bad news in a marine tank, and are a sign of an unstable system. thanks for the reference to the article. I'll read it more carefully later today.

[stingythingy45]

Phew,

Just want to say,you folks do a great job on RC,Lisa.
I'm finding that info in this hobby changes almost as fast as computers these days.It freaked me out also about nitrite,as I'm student of Bob Fenner's book(one I can't spell).lol

[LisaD]

Thanks!

I like Bob Fenner's stuff, and have learned a lot over the years from Mike Paletta, Martin Moe, Julian Sprung, Tom Frakes and others. There are some things that even with evidence to the contrary, I have trouble accepting. The concept that high nitrites aren't harmful is one of them. I will continue to keep nitrites low to zero in my tanks, but will try to remember that I don't necessarily have to freak out if I get a spike in my SW tanks.

It seems to me that nitrite spikes are more likely to occur in commercial holding systems or cycling hobby tanks than in a stable home aquarium. So I'm going to enjoy knowing more and reading a some good scholarly article with hard experimental data. But I'll still have no tolerance for nitrites in my tanks.

[billsreef]

The nitrite issue is an interesting one. It is very bad in Fresh Water, where it crosses over the gills and enters the bloodstream and binds with the hemoglobin. Much like carbon monoxide poisoning. It is sometimes referred to as brown blood disease. Where this gets interesting for us, the chloride ion just happens to block the site on the gills where nitrite crosses over. One thing our SW tanks have lots of is chloride In fact in FW aquaculture, the treatment for nitrite is to add salt. IMO that is where the old practice of adding salt to FW tanks came from.

So the nitrites themselves are not really a problem for us with SW. However, has Lisa mentioned, it is a sign of an unstable system which is never a good thing.