poorly goldfish

[LittleLambChoppy]

DH noticed the fish were looking slightly poorly yesterday and said he saw some white spots on them so he went out and brought some white spot treatment and put it in the tank. I've been away from work and got back this morning, checked the water parameters and they are in desperate need of a water change. They do have white spot and the treatment says it works over four days. If I change the water now the medicine will be diluted, but if I don't change the water they are going to be poisoned. So now I'm stuck as to what to do? Do I wait the four days for medicine to work and hope the water doesn't poison them or change the water and hope they have had enough medicine?

Anybody?

Errrr... Change the water now! Do a 100% water change and just re-dose the meds. Be sure to remove any carbon from your filters if you're using medication.

I changed the water before your reply. Have remedicated them and now just fingers crossed. Fish is staying at the bottom of the tank still but doesn't look quite as poorly as before. Do you think I should change the water again tomorrow?

Why is the water so bad?
What size fish?
What size tank?
Is the tank cycled?
How often do you normally change water and how much?
How long has the tank been set up?

I'll see if I can help

Tanks just over 120 litres, two goldfish, upgraded tank about a month ago as the fish were getting too big for the original tank, I put some of the water from the previous tank in along with done if the filter media for about 10 days before changing them over, do 50% water changes once a week. Fish are about 2-3 inches ATM.

Any ideas?

So you ran the tank without fish for ten days before moving the fish in? That's weird.

The beneficial bacteria, that converts fish waste into nitrate, live in your filter media. They don't live in the water so keeping old water isn't good. Always use fresh, dechlorinated water. Chlorine kills the beneficial bacteria.

Moving the filter media to a tank without fish in will have starved the culture to death within 48 hours. They need fish waste to feed on. You should have transferred all the filter media and fish into the new tank immediately.

The guy at the shop said that was the best way to do it so that the tank would be cycled before putting the fish in as we had to buy a new filter, gravel, plants etc as the ones we had were all too small for the new tank

Day 2 of the new dose of treatment and the white spot has already claimed one victim the other one seems to be getting worse instead of better

The guy in the shop doesn't understand a thing about cycling a tank, and unfortunately passed on his ignorance to you. Google it and you'll understand. Bacteria in the filter cannot live without food. You starved the filter culture and the tank wasn't cycled so your fish were poisoned.

He told me to put fish food in the tank each day during the process to 'feed' the tank