All My Mollys Dead! Plz Help

[barkingfrog]

Today I bought 7 mollies, most were dalmation and a few black. I also bought 3 red platys. I set them up in my tank to breed about 4 hours ago. Everything was fine and dandy an hour later. I just went to check on them and all the mollys were dead! So far the Platys seem to be doing fine. Any ideas on what could have happened? The tank was in pristine condition and just yesterday I did a 50% water change and added all the needed additives. I've had plenty of experience with fish over the years but this is my first time with mollys. Please help.
-Sad fish owner

 

[Spishkey]

ok firstly, was this tank cycled and how long had it been set up for. are there any other fish in there apart from mollys and platys and what were these 'additives' you added?

 

[barkingfrog]

The tank was completely cycled well over 3 months. There are no other fish in there except for what I just got. By additives I just meant aquarium salt.

 

[LauraFrog]

Hmmm, sounds good... this is odd. How did you cycle (did you do the proper fishless cycle adding ammonia)? How much salt did you put in? How did you acclimatise the fish you bought to your water? And have you added water ager to the water?

 

[Spishkey]

also how was your journey home with the fish and what is the weather like where you are? on another forum i have read thread after thread about peoples fish dying within hours of getting them home, purely because the fish got too cold, then shoved into a warm tank without being acclimitised properely. its strange though that all of your mollys died around the same time? how much salt did you add?

also if the tank has been 'cycled' for three months, and has had no fish in there, unless youve been adding an ammonia source daily, the tank will not in fact be cycled, there will be no good bacteria in there. then with adding so many fish at once you have overloaded the tank perhaps?

 

[barkingfrog]

The journey for the fish was only about a 10 minute car ride, and even though its only about 25 degrees (Fahrenheit) outside the fish would have only been outside for no more than 30 seconds. I added 4 tablespoons of salt since its just a 20 gallon tank. It's very strange though that the mollys died within hours while the platys are still alive (I just checked them like 10 min ago). I understand what you are saying about the ammonia levels but I had fish in the tank until just a few days ago and just got rid of them to make room for the mollys and platys. It sure is strange, I just hope I can get my money back tomorrow from the store. But you have anymore ideas on what could have happened? Thanks for the suggestions so far!

 

[Spishkey]

do you have a water testing kit? if so give us your water stats in ammonia nitrite and nitrate.
even though you had fish in up until a few days back, im am thinking that for those few days that the tank didnt have fish, some of the bacteria have died and caused the tank possibly to start a mini cycle?

if you can give us your water stats this would help us determine if this is in fact whats going on

 

[malakye]

this might sound daft but what did you do when you got them home, how did you get them from pet shop to free swimming in the tank. I just wonder if you put them into the tank too quickly and shocked them.

 

[omega59]

what are your water stats, and tank size? how exactly did you cycle this?