Molly fish reacting badly to Melafix treatment

I had a molly fish die on me the other day. It never settled well since I bought it around a month ago. It also gave birth 2 days into the new tank so I don't think that helped.

I decided to dose the tank with melafix just incase but my dalamtion molly (female) instantly clamped her back Fin and and sank to the bottom of the tank. She always does this when I use Melafix. She seem particularly worse this time round.

Now my silver molly (female) is doing the same thing as the dalmation molly (female) and my other dalmation molly (male) is darting and thrashing around.

This isn't a one off occasion. The dalamtion molly always reacts this way when melafix is used so I know it is the melafix causing this.

Any idea why and can anyone explain the male dalmations thrashing and darting?

No nitrate or ammonia present in the tank.

The tank is a 58L and currently has:
6 guppies (all males)
2 dalamation molly (male and female)
1 silver molly (female)
2 silver molly fry
4 orange molly fry
2 swordtails (male and female)

 

I would start off by stopping the melafix. Treating a tank with meds "just in case" usually causes more harm than good.

 

I always use this product when adding new fish and seeing as a fish has died, without any warning, I would assume treating the tank for disease after would be a good shout but for some reason, this fish responds badly to it every time.

 

Yeah, i would stop for awhile and see. Sounds like a stress reaction.

 

Yeah, i would stop for awhile and see. Sounds like a stress reaction.

OK will do! I have done a water change and she has calmed down a bit. The silver molly is no longer clamped which is good. Thanks for the help!

 

do a 50% water change everyday for the next 3-4 days to dilute it.

melafix and pimafix are herbal remedies. i've not seen conclusive studies/research that show it actually cures any diseases.

did you qt the new molly?