paralyzed fish

[njweiss]

Hi i have a tank with platys and mollies, yesterday morning i woke up to my black fish (idk what one she was) dead and it looked like her "skin" was peeling off which i thought was odd bc obviously they dont have skin... And now i have another fish who is acting like its paralyzed... it is moving its front fins but it looks like it cant move its tail, it can still swim a little. All of the mollies and platies are looking kinda sad... but the angels and other random fish look healthy as could be.
No clue what to do... please help..

Oh and tank temp is between 75 and 78
its a 20 gallon tank
we have white sand at the bottom and fake plants in there, i did a partial water change about a week ago, probably about 5 or 7 gallons

 

[Fishkeeper26]

Is the tank cycled?
What are your water parameters (nitrite, ammonia, nitrate)?
What are the exact fish in there and how many of each?
Do you use dechlorinator when you do a water change?
What filter do you have?

 

[njweiss]

yes the tanks been up for probably 5 months, but we origionally filled it with water from our big tank which is fully cycled
dont know, i have to see if we have a water tester kit for the big tank... and ill get back to you with that
there are 5 mollies and or platies
2 angel fish
and 5 little random fish my hub picked out from the pet store, idk what they are but they are smaller then the platies
the filter is a generic filter that came with the tank kit from walmart... it says whisper 10-30i

 

[Donkey Gun]

Need to get the water parameters before moving on..

 

[njweiss]

ok the nitrites tested as <0.3mg/l
and the ammonia test is setting now it said it takes 20 mins
do i need to test hardness and ph?

 

[Donkey Gun]

not at the moment. Your Nitrites should be zero, ammonia should be zero, and the nitrates should be low...

Let us know what your ammonia is as soon as its done, but it seems like your fish could be suffering from nitrite or ammonia poisoning.

The best thing to do is a huge water change. Also, make sure your using a good dechlorinator in the new water. I use Prime which also detoxifies trites, trates, and ammonia.

 

[Donkey Gun]

Also, just a note from your previous comment.

By just adding water from an older tank, does not mean the new tank is cycled. This is because the bacteria does not
live in the water column. What you should have done is use new water, then cut out a piece of the filter from the older tank and
place it in the new tanks filter. This is where most of your good bacteria lives.

But, if this was 5 months ago, I'm sure the tank has cycled by now.

 

[Mumma.of.two]

Did you change any media from the filter recently?
What kind of test kit are you using?
Do you add dechlorinator when you do water changes?
Do you add anything to the tank other than dechlorinator, like pH changing chemicals?
Did the fish have any white spots, fungus looking stuff, white cottony growth or anything else abnormal?
If you post a picture of your fish we can ID them for you. You tank sounds quite over stocked unfortunately.