Help Very Sick Cardinal

[topshot]

please help. i had white spot 4 weeks ago that only affected my cardinals which were then new to me by 3 weeks! treated the tank in correct way etc and it all cleared up fine. NOW ONE OF MY CARDINALS is gasping for air and seems unable to swim( floating with the tank current). i noticed it last night and this morning he has lost colour with grey patches. IS THIS VELVET?

this seems to have come on very quick.!
I have put him in a net and he seems very poorly.

I also have a platty fry in the tank will medication harm it ??? its 2 weeks old!


70litre juwel tank
4 platties (+ 1 fry)
2 pepper cories
3 guppies (new to tank 2 weeks)
3 rummy nose tetra
4 cardinals

 

[topshot]

well he didnt make it.

i did a 25% water change. should i treat the tank still for velvet do you think?

 

[IMCL85]

little guy sorry for ur lost. Hope they all get healthy.

 

[Tokis-Phoenix]

Do you have any recent stats for ammonia, nitrites and nitrates? If not you must test your water for these stats straight away, do you use dechlorinator? Avoid using meds at all for now until you know exactly what your fish died of, medicating fish can be a stressful experience for them so you do not want to use meds unesarsarily.