Rak9378
Aquarium Advice Activist
I'm no expert but I think there are a couple of factors that lead to the problems you're having. Bear with me because this is going to be a bit lengthy.
When pH is below 6.5 the nitryfing bacteria become inhibited and have a hard time reproducing. Because you had a relatively light bio load and the tank was established for over a year this wasn't too much of an issue. However this changed when you added the 12 new fish. That is a lot of fish to add at once and would put strain on the biological filtration. Normally the bacteria would reproduce quickly given the additional food source (i.e the ammonia created by the new fish) but because your pH is below 6.5 the bacteria growth is inhibited and the bacteria cannot keep up with the ammonia being added.
However I don't think ammonia poisoning is what killed the fish or is the reason the other fish are breathing rapidly and gasping at the surface. The reason is because of your pH.
It just so happens that when pH is below 7 most of the total ammonia is comprised of ammonium, the much less toxic form of ammonia. By way of background, hobbyist test kits for ammonia provide a measurement of Total Ammonia. Total Ammonia is the sum of toxic un-ionized ammonia (NH3) and nontoxic (or far less toxic) ionized ammonia (NH4). The proportion of total ammonia in the toxic un-ionized form increases with higher pH and temperature. In other words the higher your pH the more total ammonia will be comprised of the toxic form. She pH is below 7 the vast majority of total ammonia will be in the non toxic form. Even after you boosted your pH to 7 a total ammonia reading of .5 would mean that only .003 is in the toxic form (assuming a temperature of around 78). To give you context, a level of .02 is considered enough to cause long term damage and .05 is the point where fish would be in imminent danger (these levels could vary depending on the sensitivity of the particular fish). So this is why I don't believe ammonia is your problem.
So what is the problem? I believe it is the nitrite level in the tank. The high level of nitrite is preventing the fish from taking in oxygen and this is why you see them gasping. It is called Brown Blood Disease. This problem was being made worse by the low pH which was inhibiting the bacteria from reproducing. Bringing your pH up to 7 should help that. Are the fish still gasping? Any improvement? If not and your test kit is still showing 0 for nitrite it could be that the nitrite levels are so off the chart that the API test kit is not able to read the levels and just shows 0. I'm not sure why it does this but I have heard it a few times.
If you are seeing nitrite levels on your test or your fish are still gasping resting on gravel then you need to take action. Water changes would help temporarily reduce the nitrite level but it may also reduce your pH again and slow down the cycle. Sodium chloride (common salt) is known to be used as a way to negate the impact of nitrite but I'm not sure what the steps, dosing, etc so I couldn't help you there. Another option would be to use a product called Prime by Seachem which detoxifies ammonia, nitrite and nitrate.
So that is what I'm thinking. Just my opinion. I hope you find all of this helpful. Keep us posted.
When pH is below 6.5 the nitryfing bacteria become inhibited and have a hard time reproducing. Because you had a relatively light bio load and the tank was established for over a year this wasn't too much of an issue. However this changed when you added the 12 new fish. That is a lot of fish to add at once and would put strain on the biological filtration. Normally the bacteria would reproduce quickly given the additional food source (i.e the ammonia created by the new fish) but because your pH is below 6.5 the bacteria growth is inhibited and the bacteria cannot keep up with the ammonia being added.
However I don't think ammonia poisoning is what killed the fish or is the reason the other fish are breathing rapidly and gasping at the surface. The reason is because of your pH.
It just so happens that when pH is below 7 most of the total ammonia is comprised of ammonium, the much less toxic form of ammonia. By way of background, hobbyist test kits for ammonia provide a measurement of Total Ammonia. Total Ammonia is the sum of toxic un-ionized ammonia (NH3) and nontoxic (or far less toxic) ionized ammonia (NH4). The proportion of total ammonia in the toxic un-ionized form increases with higher pH and temperature. In other words the higher your pH the more total ammonia will be comprised of the toxic form. She pH is below 7 the vast majority of total ammonia will be in the non toxic form. Even after you boosted your pH to 7 a total ammonia reading of .5 would mean that only .003 is in the toxic form (assuming a temperature of around 78). To give you context, a level of .02 is considered enough to cause long term damage and .05 is the point where fish would be in imminent danger (these levels could vary depending on the sensitivity of the particular fish). So this is why I don't believe ammonia is your problem.
So what is the problem? I believe it is the nitrite level in the tank. The high level of nitrite is preventing the fish from taking in oxygen and this is why you see them gasping. It is called Brown Blood Disease. This problem was being made worse by the low pH which was inhibiting the bacteria from reproducing. Bringing your pH up to 7 should help that. Are the fish still gasping? Any improvement? If not and your test kit is still showing 0 for nitrite it could be that the nitrite levels are so off the chart that the API test kit is not able to read the levels and just shows 0. I'm not sure why it does this but I have heard it a few times.
If you are seeing nitrite levels on your test or your fish are still gasping resting on gravel then you need to take action. Water changes would help temporarily reduce the nitrite level but it may also reduce your pH again and slow down the cycle. Sodium chloride (common salt) is known to be used as a way to negate the impact of nitrite but I'm not sure what the steps, dosing, etc so I couldn't help you there. Another option would be to use a product called Prime by Seachem which detoxifies ammonia, nitrite and nitrate.
So that is what I'm thinking. Just my opinion. I hope you find all of this helpful. Keep us posted.
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