Help! Fish are dying... what did I do wrong?

[bluwtr]

I would say yes. pH, salinity, and Alk shock are big reasons why a lot of critters die when introduced. Another reason is just stress from all of the collection/travel/handling.

[ReneM]

Thank you


I need a book on all this stuff! LOL

[Doug]

I began a reply to this thread the other day, but didn't post it. I should have gone with my initial impression, but after re-reading the original post, I second-guessed myself and said "sounds like pH shock, but it's been almost two weeks, so maybe not, and someone else has a better idea I'm not aware of". What is does point up, however, is that aquaristic professionals often make basic assumptions about the scenarios presented to them, and those assumptions lead them to overlook the root of the problem.

We preach that change is the enemy, but by that we really mean rapid change. Truth is, fish can put up with water quality parameters being wildly out-of-whack, as long as the deviations take place over a relatively long period of time. In this case, an inadequate partial water change regimen allowed pH levels to decline. The fish already in the tank didn't mind, as it happened over time. But the addition of a large amount of new water, even though it was temperature matched, represented a huge sudden change in pH to them. In retrospect, even if there was not a move to a new tank, a new fish introduced to the old tank, and acclimated for the store-recommended amount of time may well also have been pH shocked and stressed, too.

I am reminded of a similar incident years ago, and relate it here for educational purposes: A customer complained that every new saltwater fish she bought from me died, but all the fish already in her tank were fine, so the fault must not be with her tank. As a courtesy, I agreed to come to her house and test her water. The first thing I noticed upon arrival was a glass hydrometer floating in the tank. My impression was that this was of no real use, as the glass canopy was preventing the hydrometer from floating freely, and, therefore, it was not showing an accurate reading. Once the canopy was opened, the hydrometer floated up and settled on a reading of 1.032. Yes, that's not a typo. After a few well-chosen questions, it was discovered that the customer had been for many months topping up with saltwater to make up for evaporation, rather than with freshwater. Over time, the salt level in the tank had crept up slowly, and the residents within had adjusted to it. New fish, however, were subjected to a specific gravity difference from 1.020 to 1.032 in the span of only 20-30 minutes. That they died within hours was no longer a mystery.

[Gerwin]

Doug and Blu are spot on, but ph is but one issue as Doug mentioned in his ex. of the super salted tank, Nitrates are another as well as even nitrite and ammonia all can be high levels but a lightly loaded tank that has been set up for months or years that is neglected...well the fish sorta adjust to the gradual decline , to a point. But then the new fish gets put in and goes into all kinds of stress.... IMO you are lucky if it just dies, more often it becomes ill and now you are fighting disease which often takes the blame for the death and then antibiotics are poured in only making a bad situation worse. Its why I attempt to always get customers to bring me water samples so I can see about the basics of the eater quality.