New Fish Dying

hi guys, in the last 2 weeks i have bought new platys from pets at home which i normally buy my fish. the first 2 i bought died within 48 hours, they replaced these and now within 48 hours  1 has died and the other looks to be on his way out. he seems to have no control of where he's going and he's  at the bottom of tank or stuck to the filter.  i have started swim bladder treatment to see if i can rescue him.. 
my other 2 platys and 4 cardinals have been fine..  my test are all zero except ammonia which was .25 which is lowest i can get it due to mains water having ammonia in ..   any ideas why they all seem to be dying, thanks

hi richard, ammonia level is under .25 from tap wt wierater as its a light green in colour when tested so i know its in there, i clean my fish regular and test regular,. my ph is always low about 6ish but not had probs in past with this.. just weird the new one are dying .. the pet shop even tested water and said it was fine ....  moving them to my 60l tank next week so maybe a bigger tank will be better for them ..

The pH is the thing that does jump out, especially as platies ideally prefer hard alkaline water.

Fruitbat, how do you transfer the fish from the bag to your tank or in other words, how do you acclimatise the fish?


And on the subject of ammonia, if you are using the API tester, it is notorious for not being able to read the zero colour. Many people report never getting rid of that green tinge even with tanks that have been running trouble free for many years.

It depends on whether you actually do have a reading for ammonia or whether is it a false reading due to the limitations of the testing kit. If the ammonia reading never drops below 0.25, that does suggest you are getting a false reading - this is more common than you'd think.
In which case you do need to add ammonia. Even if you had 0.25 ppm in your water that would not grow very many bacteria.


With your low pH, you might try drip acclimatisation next time. Empty the bag of water and fish into a bucket. Using a length of airline tubing, tie a lose knot in it then start siphoning water from the tank to the bucket, tightening the knot to give a flow rate of a few drops per minute. At this time of year you might need to put a heater into the bucket as well. Once the volume of water in the bucket has tripled, net the fish from the bucket into the tank.
This method changes the pH (and hardness and anything else in the shop water) very slowly giving the fish time to adjust.

So I'm going to be the second person this week to disagree with Sue 
The evidence is that fish can only adjust very slowly to water parameters such as pH, hardness and concentrations of nitrate etc., so that slow mixing of water e.g. by the drip method is a waste of time.

In fact the ThinkFish article on introducing fish is spot on, as usual, and says :

Myth buster
"Adding tank water to the bag of new fish every few minutes will help acclimatise them. If you are acclimatising freshwater fish the only parameter that can be equalised in a short period of time is temperature, which is best done by floating the fish for 15-20 minutes. Fish may take days or even weeks to fully adjust to changes in pH, hardness and water pollutants, so mixing will not help, and may even further stress the fish during their temperature acclimation."

I also disagree  with the usual idea of equalising the temperatures by floating the bag in the tank, then pouring the fish and their water into the tank. Doing this you may be adding pathogens to your tank, not to mention an extra dose of ammonia.  I equalise the temperatures, then pour the water out through a net to catch the fish so that only the fish and a tiny amount of their water goes into the tank. This is not my idea, of course, many sources suggest the same.

Neither the drip method nor adding a cup of water is any use. A fish's physiology is simply incapable of adapting over an hour or so, it takes days or weeks.

So I can stop adding a bit of water to the bag for an hour or so. That'll save some work