Fish Fins Clamping Please Help

[donna123]

ive just looked in my daughters tank 3 out of 6 fish have clamped fins,they are platy and guppy babys,
could it be the water or something else,all other fish are fine, we set it up on sat with sponges that i matured in main tank for 2 weeks,
63ltr,
ammonia 0.50
nitrIte o
nitrAte 5.0
they are eating but seem to hang up at the top, ive done a 50% water change for now,
will the fins become unclamped if its the water?
edit now all fish are clamping ammonia now 0.25 nitrite 0 nitrate 5.0,
there was a strange looking blue rock which ive now taken out,it was blue and white,looks like a mineral rock.
now ive had to remove all fish,i need to find out what went wrong before i try and restock.

 

[WILDER]

You have ammonia readings, that why they have been fin clamping, ammonia reading should be 0.

 

[donna123]

all fish moved to hospital tank still have clamped fins,the tails look pointed,
will they recover? hospital tank ammonia 0.

 

[WILDER]

Should do if water quality is good now, good luck.