Freshwater conditioner

Question
Hi I've recently set up a freshwater 25 litres tank and have (had) two fancy goldfish. One of them got sick with this furry white disease which ate away it's tail. I treated it with Fungus Cure malachite green and acriflavine. I'm worried the  other fish in the tank might get it too but so far it looks ok except for his tail which looks a bit limp. I bought a heater and changed the water, added some salt. Do you know what disease my other fish had? Should I add a water conditioner or is salt enough? Thanks a lot for your help. I really appreciate the fact that you are doing this for free. Best wishes, Clare in Australia.

Answer
Hi Clare,

Please increase the size of the tank, or get a different species of fish.  I can explain what's going on and why.

First of all, even a baby goldfish requires 10 gallons.  Just one.  The fish is one of the fishes who poop an extreme amount and it also dissipates into micro poo, so the fish ends up swimming in its own sewage, and this causes chemicals to form.  Those chemicals are nitrates, nitrites and ammonia (amongst others) and those three are deadly.  Nitrite/Ammonia poisoning is absolutely deadly.  The symptoms are furry white disease which eats away at fins, tails, streaks of white in fins and tails, bloody fins and tails, listlessness, sitting at the bottom and unable to swim far, and swimming at the top, gulping air, and not able to swim down.  Swim bladder disorder amongst other things are caused by the combination of filthy water and too much food.

Goldfish of 3" of more require 25 gallons.  25 gallons is 100L.

This means your fish are not just overcrowded, they are extremely overcrowded.

You know how you see fish bowls on tv?  They're not appropriate and goldfish suffer terribly in them, so it's good that yours at least isn't a fish bowl, but these problems will continue as long as there are two goldfish in such a small area.

I advise no more medications.  Please.  Just get a bigger tank, or find another type of fish which requires less space. :)  It's the best cure.

The white fungus on the first fish would not have happened if the skin had not been eaten away by poison in the water caused by poop.

I would not add salt.  Nothing but water conditioner when you do water changes.  Also, something you might not know is with goldfish you need to change water every single weekend.  In your case, every 3 days, half the tank of water.  Every weekend, with one goldfish, 25% and if you have regular fish, change it bi-weekly at the rate of 25%, even if you have a filter.

I hope this is helpful.  Your experience can be fun and wonderful.  If you get this under control now, it will be. :)  I wish you the best.  Ask questions anytime.

Happy fish-keeping.