What's wrong with my goldfish?

[tinyheed]

Have 3 goldfish in a 20 ltr tank(2 black 1 gold).
Noticed in the last week that the gold one has been acting strangely. One minute he's on the bottom hiding behind stuff then he's at the top like he's tring to eat.

Also his fins top and bottom are gone, not sure whether they,ve dropped off or they're just folded up. it's only affecting the goldfish

Tried changing the water a couple of times but it's still very strange.

Any help appreiciated

[dustypuss]

its fin rot get some stuff from you pet store to put in the water

[showcatbenga]

Do you have a filter? Have you tested your water for ammonia, nitrite & nitate? Are you using a dechlorinator for your fresh water?
It sounds like your gold goldfish has fin rot & possibly swim bladder problems.
First thing you can do is to add 1 to 3 grammes of aquarium salt (NOT cooking salt, poisonous additives) for each litre of water. Dissolve the lowest dose of salt in a litre first & then add to the rest of the tank mix well or the salt solution will sink to the bottom & burn the fish's gills & fins. This should perk up all your fish & will help with swim bladder problems & constipation.
The next thing to do is to get a fin rot remedy from the local fish or pet shop. Follow the directions exactly. It doesn't matter that you have salt in the water, it won't affect the way you should use the remedy. If you can do this a quick as possible you may be able to save your fish.

[Matkop]

3 goldfish in a 20 litre tank seems very overcrowded, unless they are tiddlers (less than a couple of inches).

Goldfish pollute the water with their waste very quickly - the 'normal' guideline for goldfish is at least 40 litres tank volume *per fish* when they are grown up!!

Otherwise you will need a good tank filter and a *lot* of water changes (30% every week at a minimum). Don't forget these guys are "swimming in their own loo", so the toxins build up fast - and that causes stress, which then causes the fish to get ill very easily.

As showcatbenga says, you need to test for Ammonia & Nitrite (they tolerate Nitrate quite well, but every fish has a limit!) and make sure the water quality is good.

Always in fish keeping, 90% of problems will be fixed (given enough time) by getting the water quality sorted out. Hopefully your 'goldie' will pull through. Good luck!