Best way to restart tank?

[BuckeyeLeafs]

I have an Eclipse 12 gallon that has been set up for about 3 or 4 weeks. I bought two fancy goldfish from Petco to stock the tank with. I had to euthanize one of them last Sunday because I knew it was going to die, it had been laying on the ground of the tank, hiding behind a piece of wood for days. I know that this fish had some sort of parasite, but hoped that the other one would be able to fight it.
I now think that I will have to euthanize the other fish very soon. I am not sure what is in the tank, I couldn't tell if it was Ich or not because I only could see white 'salt-like' crystals on the tail fins of the first fish when it was directly under the light and I don't know if that was just relflection/etc. On the 2nd fish I noticed a parasite on its tail, it look like brine shrimp without a tail, if anyone something that looks like that, I couldn't find anything online...
So, I am going to put the last fish in my freezer, and am wondering what to do to clear out the tank of any parasites and get it ready for new fish. I would like to keep my cycle alive if at all possible, I would feed the tank fish food to do so. I don't have a heater, so that option is out. Would it be safe to fill an acrylic tank with scalding water? Will that kill the beneficial bacteria and or the parasites?
Sorry for the long post, and btw I did try to treat with salt, and I do know that the fish will grow large, I plan on getting a larger tank very soon, plus I did do daily water changes, use conditoner,etc...
Thank you so much.

[Northernguy]

Welcome to the fabulous AC!
Your cycle will die without fish.You can use liquid ammonia to keep the cycle but not if you are tearing down the tank to clean it.
I doubt your tank was fully cycled.Did you test your water?
We need to know what your ammonia,nitrites and nitrates are/were.
Do you have a test kit?
How did you cycle the tank?

[LethalResistanz]

Never kept goldfish before but from what I here they are very messy.
for a 12 gallon tank I would think that the died from ammonia poisoning, nitrate poisoning or a combination of them both.

How big were they when you put them in the tank?
What period of time in the 3 weeks you had the tank did you add the fish?

Not sure about fancy goldfish but the common goldfish can get a foot long! I'd wait until you get a bigger tank before trying again.

There are some really cool small tropical fish you can keep in a tank that size if you get a heater, but even a single goldfish wouldn't work.

[BuckeyeLeafs]

Unfortunately, I do not have a test kit, but will be picking one up next time I go to the store. I changed the water everyday, because I figured even if the ammonia was high that would be the recommendation.
I think that the fish may have been diseased to start with, but IDK, it all happened so fast, it makes me believe that. The only thing I can think of is that I keep my apartment at about 64-65 degrees, do you think that has anything to do with this?
I won't be getting my new fish from Petco, and will probably go with a tropical setup on this tank after cleaning.
I guess I am just going to break this tank down and clean everything to make sure that the parasites are gone. What should I do that is safe and will kill everything? Is untreated tap water enough? I have a biowheel that I will have to clean somehow and I will just replace the filter cartridge.

Thanks for the help.

[BuckeyeLeafs]

They were about an inch long, tail included. I added them both at the same time, after the tank had been up and running for 3 days.

[LethalResistanz]

The petco were I live does free water testing, but I would highly recommend(if not tell you) getting a test kit for at least ammonia and nitrate. I never used a nitrite tester and I turned out fine but it will make things much easier.

These test kits will tell you when your tank is cycled, without a proper cycled tank every fish you buy will die sooner or later and it will be just a waste of money and fish life.


Again never keeping goldfish I think they can live at pretty much an room temperature.

As for getting rid of parasites if you really think you have them I'm not sure. I would assume if you just empty the tank and change the cartridge then let it dry up for a few days they would be all dead? Though I would wait for someone with more experience.

But again in all probability the tank wasn't cycled and they died from ammonia, nitrite or both.


I've made some mistakes in my day so don't feel bad.

You could also look into doing a fishless cyle if you can find some pure ammonia.