Goldfish Eye Problem

Question
Required Information;
How many fish in the tank: 1
Fish tank size: 50+ cm
Filtration System: Non
Frequency of Water Change/Tank Clean: Every 3 Weeks
Addition to Water: Oxygenation tablet
Nutrition: Non floating food pellets

Fish Characteristics;
Species: Common Goldfish
Sex: Female
Age: 6

Dear Jaymie Johnson:

I recently changed the water in the tank, I saw that the gravel was slightly dirty. Therefore I removed the gravel and gave it a wash with a small amount of soap. I washed out the soap thoroughly with distilled water. This is the procedure I go about every time I change the water. (Clean gravel, Add Clean Water and Oxygention tablet)

  After placing my fish back into the tank I realised that she was floating at the bottom, with a lack of movement. I reached the conclusion the water was maybe too cold, so I removed some. Adding warm water very slowly, in small amounts- To avoid too sudden of changes in temperature (Over a period of 45 mins). A while later, my fish started to move much more energetically.

  Although after a couple of days, I checked the tank. Her movement was great, unfortunately I realised there was a large pocket of a watery fluid accumulated on one eye of my fish. This pocket is quite noticeable. Seems she had lost sight as she would continually pump that eye into the tank walls, I feel she lost the ability to calculate distances.

  I'm very considered this was due to my cleaning procedure, I'm unsure as to what maybe the cause of this problem. Can you in anyway help me by identify what my be the problem and whether or not it can be treated?

*Also can you recommend any nutritious and highly oxygenating plants that I can install in to the tank?

Thank you very much for reading.
Britney

Answer
Britney,
Lets start from the beginning so that I do not leave anything out. 1 goldfish has to be in a tank no smaller than 20 gallons. They absolutely need to have a filter. If the tank is 20 gallons, the filter should be fore a 30 gallon or more. The tablets you are using do not do the work they are said to do, so I would stop using them. Add an air stone to the tank and that will add oxygen to the water. Goldfish are cold water fish so adding warm water will do more harm then good. You should never clean anything that is going in an aquarium with any kind of soap. I have known so many people that have done that and lost their fish. You should be doing water changes every week. Since you do not have a filter you should be doing the changes at least every other day. The problem you are having with your fish is due to very bad water quality. In order to help your fish you should get a bigger tank, definitely get a filter and do weekly water changes. Once you have done all that, you can treat your fish and have a better chance of healing the problem.