Fish Are Going Really Thin Then Dying Please Help

[lexi93xo]

hiya, i did post this on here before but cant find the add, my platties and mollies are going really thin, then 2-3 days later they are dying, ive been testing my water recently and its all fine, ive added moss balls in the aquarium to keep the water good, i feed them live food twice a week to fatten them up, the skinny fish eat perfectly fine and they do get bellies on them, but then the next day they have gone thin again, i really dont know why i have lost 7 fish from this i havent lost a fish for a week now though, but still have thin and bent one, some days they look thin and bent, some days they just look skinny, im at a loss with this, and i have junior fry that i need to take out of the fry tank but obviously i cant put them in the tank as i dont know whats up with my fish, can anyone please help me 

i need to add more pics, but unsure how to does anyone know?

 

[BerryAttack]

probably an internal parasite, treat with methylene blue (treats almost everything) ... do a large water change before hand... like 75% with treated water.... 
 
if you are cleaning your filter with tap water you are recycling your tank over and over, which isn't good. 
get your water stats.. how long have you cycled the tank?
 
you can tell if it is an internal parasite because the body will thin out (depending on which one you have) the poo with be white and stringy and the fish usually stops eating and just looks very unhealthy.

 

[lexi93xo]

they still eat like pigs, have had the tank nearly three years, i leave my filter for a bit until i clean it out

 

[star4]

My suspicion is that you (not you the fish ) have camalanus worms. They are difficult to spot as not always the fish will have stringy poo with these worms. Have you noticed any red threads hanging from the fish's anus by any chance, they will poke out of a fish when it is still, or when the worms are about to drop the eggs. The most affective treatment for camalanus worms is Sera Nematol. This is a brilliant treatment but you do have to do an 80% wc after treatment.

 

[lexi93xo]

have never noticed anything like that, they do have like stringy poop not all the time though, and it has been like a clear colour if you know what i mean 

how do i add more pictures?

 

[star4]

If you have not seen any it could be another type of internal parasite, a good general medication is Sterazin made by waterlife, I have used that before and it is good, However if symptoms persist then its camalanus worms which sterazin will help with but not kill off entirely. Sorry I can not be 100% specific for you

 

[lexi93xo]

can i get sterazin from a pet shop? i just want them all better 

 

[star4]

Most good shops sell it and it is also available on Ebay

 

[lexi93xo]

thanks will look into getting some to see if it can do anything 

 

[lexi93xo]

i now have one of my female mollie junior dry dying due to it being skinny and bent

 

[star4]

Have you added the sterazin?