Guppy Tail Rot??! Help

I don't know what's wrong with my guppies. Yesterday I changed the water it went cloudy but today the water is back to normal but my yellow guppy wasn't well yesterday and I thought he was dying as he was at the bottom of the tank and not swimming properly then this morning he's not dead but still not swimming properly and his tail isn't right and nor is one of my female guppies :/ other fishes tails are normal I've taken some pictures but don't know what the **** to do or what it is it sounds like tail rot. I had one guppy who's tail started to tear away and then he died a day later.
Does anyone have any knowledge on what this could be please

Female




Male

 

Yes it is definitely a tail rot as you can see the border of the tail is slowly rotting and is bit black along the edges. I recommend you turn the heater and maintain the tank temperature and if you can separate them to a quarantine tank and treat them, there are lots of medicines available for tail rot get the best one by consulting with the fish store owner who is experienced with the medication.

 

What size is the tank?

Also I notice your profile says you don't know of the nitrogen cycle, which is likely playing a part (the page here explains it better than I could). Since the guppies are already in I'd recommend buying a bottle of Tetra SafeStart, this will help get you through a fish-in cycle.

 

also go through the following link for the step by step curing of fin/tail rot

hope it helps and good luck

 

Thanks everyone. I have a 64 litre tank.
And because it's been so hot the heater is off and the temperature is still 28oC/81oF and that's with the heater off!! Normally It's between 25/26oC in the green zone. I don't know what to do to keep the temp down and yes I'm going to the fish shop today. I use the tetra aquasafe
Should I do another water change again I done one yesterday when I noticed the yellow one not feeling well

 

Thanks everyone. I have a 64 litre tank.
And because it's been so hot the heater is off and the temperature is still 28oC/81oF and that's with the heater off!! Normally It's between 25/26oC in the green zone. I don't know what to do to keep the temp down and yes I'm going to the fish shop today. I use the tetra aquasafe
Should I do another water change again I done one yesterday when I noticed the yellow one not feeling well

Did you go through the link I shared it is very helpful you can work according to the instructions provided in that link.

 

Yeah I'm definitely going to read it. Thank you for helping

 

Yeah I'm definitely going to read it. Thank you for helping

you are welcome , hope your fishes get well soon, and remember fin rots are communicable diseases, tail rot can spread through shared nets so be careful about that too