Question
I've had this goldfish for around 2 years now, and have no problems with it at all. I changed it over to a bigger tank (22 litre) around 3 to 4 months ago, and until now have had no issues. The tank has NO other fish within it, and just some standard plastic trees and gravel.
Every 2 weeks I change the water (around 25%) and also use "fish safe" water conditioner to try and remove some of the impurities within the water. I also use a manual vacuum to clean the fish gravel.
I'm unsure whether I've just not noticed, or whether this has happened in a small time frame, but the back fin on my fish is starting to look a bit ragged.
The other fins appear to be fine; I thought the black marking may have been a sign of poor water quality, but they seem to have been like that for over a year now.
Additionally, it seems to be swimming in one corner of the fish tank, which is very unusual for this fish as he/she is usually happily swimming around the whole tank.
I have given it some "disease safe" product, but as I'm unsure whether this is an actual issue, I don't want to overload the tank with lots of chemicals it doesn't need.
I've attached some images below to help clarify what I'm referring to.
Would any fish/pet experts be willing to offer some advice?
Thanks!
Answer
Your fish does have finrot. The cause for this is often poor water quality as a result of a build up of ammonia or nitrite in the water.
If a tank is not properly cycled, you will not have the useful bacteria that convert fish waste into nitrate (plant food). Please take a look here on how to cycle a fish tank.
To kick start a tank you can use the filter from an old tank and run this for a couple of weeks to seed your new tank.
First aid against nitrite poisoning is to add 0,3% of aquarium salt. Most fish in the carp family (goldfish/koi) will handle this concentration with no problems.
Be very careful in using medication in your tank as most types of medication will kill all the bacteria in your tank. This means you will have to cycle your tank again.
To avoid this, you might set up a hospital tank so you can treat only the fish that is ill and not destroy the biological balance in your main tank.
A 22 liter tank is too small for a goldfish. A minimum tank for one single goldfish is 60 liters and a larger tank will be easier to maintain with less fluctuations in water quality.
Answered By - trond hansen