Sorry to jump in here with all the other posts. But osmotic shock can really do a number on fish. Without kh and gh and tds numbers on both tank water and fish store water we might not be able to tell what the cause of death is. pH can possibly be used as an indicator of low or high kh but not always accuratly. The other problem now is that if the tank has had some frequent water changes since the deaths have occured we might not know how bad things were. Have the kh and gh of your tank tested and compare those to the tanks from the store. The more similar they are, the less acclimation time you need. The less similar the greater the acclimation time. Also test your tap water. It should be fairly close to the tank water in terms of ph, kh and gh. If it is far off, sounds like OTS has set in. The older fish would have acclimated to the change in conditions, new fish can't.
Fish die after a few hours - Need Help
- Thread starter captainhook
- Start date
injunear - the thing is, pH swings in and of themselves, even if caused by low KH, will not harm the fish unless the pH drops so low that acidosis sets in - around pH 4.5 to 5.5 for most species. As I said earlier, well planted tanks under good lighting will see large swings every day, and the fish thrive.
As TKOS says (superb post, btw) it's osmotic shock which is the problem, not pH. The low pH is simply an indication that the water chemistry in terms of GH and TDS may be quite different to the tap water - these parameters may be far lower, and this will cause osmotic shock when fish are moved into it. Tap water is seldom below pH 7 because of the effect it has on metal pipes if it's acid; what generally happens in softwater areas is that the water company adds an alkali to artificially raise the pH. If that's what's happened here, then the low pH in the tank is of little consequence. On the other hand, it may be that this is moderate to hard water which is being acidified by organic acids; when this happens, the various minerals will also be slowly precipitated out, leading to tank water which is lower in TDS and hardness than the tap - and LFS - water, hence osmotic shock when new fish are added. It may be, it may not, hence my request for KH/pH/GH readings of the tap water as well as the tank. LFS water change regimes are such that their water is generally pretty much the same as the tap.
It would be particularly bad for mollies, because they're high TDS fish, so they will take a sudden move from high to low TDS water - i.e. away from what they're adapted for - even worse than fish which actually prefer low TDS as long as they're not asked to adapt over just a few hours.
Which raises another issue about acclimatisation - it's widely believed now that fish cannot adapt to different osmotic pressures in a few hours - they actually require days to make the necessary physiological changes. This may not be the case with estuarine species which may in the wild have to experience two changes from salt to fresh and back again in the space of a day, but that's not because they withstand the osmotic changes but because they're adapted to cope with them. Most fish aren't.
As TKOS says (superb post, btw) it's osmotic shock which is the problem, not pH. The low pH is simply an indication that the water chemistry in terms of GH and TDS may be quite different to the tap water - these parameters may be far lower, and this will cause osmotic shock when fish are moved into it. Tap water is seldom below pH 7 because of the effect it has on metal pipes if it's acid; what generally happens in softwater areas is that the water company adds an alkali to artificially raise the pH. If that's what's happened here, then the low pH in the tank is of little consequence. On the other hand, it may be that this is moderate to hard water which is being acidified by organic acids; when this happens, the various minerals will also be slowly precipitated out, leading to tank water which is lower in TDS and hardness than the tap - and LFS - water, hence osmotic shock when new fish are added. It may be, it may not, hence my request for KH/pH/GH readings of the tap water as well as the tank. LFS water change regimes are such that their water is generally pretty much the same as the tap.
It would be particularly bad for mollies, because they're high TDS fish, so they will take a sudden move from high to low TDS water - i.e. away from what they're adapted for - even worse than fish which actually prefer low TDS as long as they're not asked to adapt over just a few hours.
Which raises another issue about acclimatisation - it's widely believed now that fish cannot adapt to different osmotic pressures in a few hours - they actually require days to make the necessary physiological changes. This may not be the case with estuarine species which may in the wild have to experience two changes from salt to fresh and back again in the space of a day, but that's not because they withstand the osmotic changes but because they're adapted to cope with them. Most fish aren't.
Yes, I remember you stating this in another thread.........
So the low PH is symptomatic and in and of itself may not be a problem? Correct?
Interesting.....I didn't know that!
Ok, got it! But what is the source of these organic acids? Plants? Ammonia (not sure if ammonia is alkaline or acidic) ?
I see now where you would need this info..........
Excellent information.....BTW, I see the term Old Tank Syndrom (OTS) used again. What exactly is OTS?
Thanks
Ammonia is alkaline, but the organic acids are produced by various bacteria and fungi which break down all sorts of waste products in the tank. pH tends to drop over time also because the process of converting ammonia to nitrate uses up bicarbonate (KH), which causes a drop in KH and a corresponding drop in pH. A tank therefore which is seeing pH considerably lower than tapwater inclines one to suspect that KH is very low; this is bad for a couple of reasons:
1. Bacteria can't convert ammonia if there's no bicarbonate;
2. The same bacteria can't work at very low pH;
And, of course, if there's nothing to stop the crash, a very low pH where acidosis can occur may be the end result.
It's also very dangerous to cure. You might imagine that you can just raise the KH (bicarb does the job) and all will be well. But often the fish, to the aquarist's surprise, drop dead as soon as he does this. This is because of the inhibited bacteria. If they are inhibited by lack of bicarbonate and low pH, then ammonium builds up - this is the non-toxic NH4+ form, which predominates in acid environments (plenty of H+, you see, to combine with NH3). As soon as the bicarb is added, the pH rises, but this causes the NH4+ to convert to NH3 - toxic ammonia. And this can kill fish fast. A rise of 1 pH point effectively makes the NH3/NH4+ ten times as toxic, because as has been observed, the pH scale is logarithmic. A single point is a ten fold decrease in the concentration of H+ available, which leads to a ten fold increase in the amount of ammonia in the toxic NH3 form. pH drops therefore shouldn't be treated by raising the KH until the NH3/NH4+ level has been checked (fortunately, aquarium test kits give ammonia as total NH3 + NH4+; the disadvantage of this is that you need to cross-reference with pH to find the level of NH3. This doesn't matter much as we always want it to be 0 anyway).
This phenomenon is also part of OTS, because it's caused by insufficient water changes to maintain a steady KH (main means of replenishing bicarbonate is from water changes). Another indicator is high nitrate, because the same water changes are also the means of removing nitrate, but in a planted tank this indicator may not be seen.
Clearly this tank hasn't got to this point yet, because ammonia is reading 0 and nitrate isn't high. But I'd want the GH and KH compared to tap to see if it's heading in that direction, and if there is a difference which is contributing to his current problems.
Whew! How can a simple chemical like H2O have such complex chemistry? Actually, it doesn't, it's the bleedin' things which dissolve in it!
1. Bacteria can't convert ammonia if there's no bicarbonate;
2. The same bacteria can't work at very low pH;
And, of course, if there's nothing to stop the crash, a very low pH where acidosis can occur may be the end result.
It's also very dangerous to cure. You might imagine that you can just raise the KH (bicarb does the job) and all will be well. But often the fish, to the aquarist's surprise, drop dead as soon as he does this. This is because of the inhibited bacteria. If they are inhibited by lack of bicarbonate and low pH, then ammonium builds up - this is the non-toxic NH4+ form, which predominates in acid environments (plenty of H+, you see, to combine with NH3). As soon as the bicarb is added, the pH rises, but this causes the NH4+ to convert to NH3 - toxic ammonia. And this can kill fish fast. A rise of 1 pH point effectively makes the NH3/NH4+ ten times as toxic, because as has been observed, the pH scale is logarithmic. A single point is a ten fold decrease in the concentration of H+ available, which leads to a ten fold increase in the amount of ammonia in the toxic NH3 form. pH drops therefore shouldn't be treated by raising the KH until the NH3/NH4+ level has been checked (fortunately, aquarium test kits give ammonia as total NH3 + NH4+; the disadvantage of this is that you need to cross-reference with pH to find the level of NH3. This doesn't matter much as we always want it to be 0 anyway).
This phenomenon is also part of OTS, because it's caused by insufficient water changes to maintain a steady KH (main means of replenishing bicarbonate is from water changes). Another indicator is high nitrate, because the same water changes are also the means of removing nitrate, but in a planted tank this indicator may not be seen.
Clearly this tank hasn't got to this point yet, because ammonia is reading 0 and nitrate isn't high. But I'd want the GH and KH compared to tap to see if it's heading in that direction, and if there is a difference which is contributing to his current problems.
Whew! How can a simple chemical like H2O have such complex chemistry? Actually, it doesn't, it's the bleedin' things which dissolve in it!
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In short, it is the build up of TDS, hormones, etc. as a tank ages. Generally, these are adressed during our maintenance routine. However, this occurs given a poor routine or a slow appreciation of these concentrations over-time, which in turns requires the aquaria (fish, etc.) to slowly acclimate over time to these conditions.
When people refernce OTS, they are often doing so in relation to its effects 'after-the-fact'. In otherwords, an Aquariast will introduce a new fish and they fall "ill" from some unknown ailment. The Big-Three all test out okay (Ammonia/nitrItes/nitrAtes). They then perform a large WC, as the symptoms often manefist as poor water conditions as the fish suffers from a secondary infections. This in turn, 'shocks' the established fish (ie. osmotic shock or suffering) and in extreme cases, can cause a mass die-off...
Good discussion BTW
One week has passed and I have not completed a water change yet.
I tested the water again and have to following readings:
PH = 6.0
Ammonia = 0
Nitrite = 0
Nitrate = 40 (last week this was 20-40)
I am going to complete a 25% water change now.
What should I do to address the low PH level? The test kit suggests adding a PH additive to raise the level.
*I tested the PH of my tap water and it is 7.6 on the ph test and 8.0 on the high ph test.
I tested the water again and have to following readings:
PH = 6.0
Ammonia = 0
Nitrite = 0
Nitrate = 40 (last week this was 20-40)
I am going to complete a 25% water change now.
What should I do to address the low PH level? The test kit suggests adding a PH additive to raise the level.
*I tested the PH of my tap water and it is 7.6 on the ph test and 8.0 on the high ph test.
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