Hi Patty. I believe what's going on is basically
the goldfish have outgrown the tank. Goldfish are
pretty big eaters and also tend to "go to the bathroom" more than most fish. As a result of this, more ammonia is created therby affecting
the water quality which is why you're seeing the cloudy water (a bacterial bloom). The goldfish have gotten bigger hence more excretion hence
more ammonia. Apparently the filter cannot keep-up with the bio load. The end result of all this is poor or unfavorable water quality which leads to stressed fish which leads to disease.
From the information you have given I would say the fish are suffering from a condition known as fin/tail rot which is a bacterial disease usually caused by poor water quality.
So the first thing I urge you to do is test the water using a standard test kit which can be bought at most pet shops that sell fish. If you
feel uneasy about performing the test bring a sample to a fish pet shop and they will usually do it for free. You'll want to test for ammonia,
nitrite and nitrate levels with ammonia and nitrite being the most critical and dangerous.
Next, buy an anti-baterial medication made especially for fin rot. There are many so that
when you go to the pet shop you can either read the product label or ask a store employee for
the medicine. The brand name isn't of importance.
Begin to treat the fish tank following the instructions on the product label.
I strongly suggest that you get a bigger tank for these 2 goldfish, at least 20 gallons, as is always the case with fish, the bigger the tank the better. Meanwhile cut down on the amount and frequency of feedings so as to ease the burden on the bio load and lastly--perform more water changes, to make life easy--2 gallons every 3 days if and until you can get a bigger tank.
Please note--Goldfish are notoriously messy fish
and therfore you must be vigilant of their water conditions. I have listed below a web page that will give you a brief synopsis of the disease=
fin/tail rot. I truly hope everything turns out
OK. Please let me know if you need further assistance.
