Many goldfish are imported in very cold water, in crowded conditions, making them very susceptible to disease (especially ich). Although goldfish are not very particular about water conditions, they still do better at a ph of 7.2 to 7.8 and a high mineral content (especially calcium and magnesium- KH of 80 ppm or more).

Goldfish also are basically grazing fish and need to be fed frequent small amounts of fish food that are not made from animal based products. Goldfish do well on foods high in vegetable based proteins (such as spirulina), they need a high fat content and Vitamins C & E, and carotenoid for color enhancement.

Canister filters are great for goldfish, due to there high efficiency and great bio load and mechanical filtration abilities (although make sure to clean them regularly, or they become nitrate factories). Unfortunately they are generally expensive. A combination of hang on back filters (such as ReSun and Aqua Clear) and sponge filters are an excellent combination for less money.

Regular water changes are a must. A small 20% change once per week is best (sometimes larger less frequent changes can be performed as per ones busy schedule). Using a gravel vacuum is the best and easiest way to change water (a new device called an "Aquarium Cleaning Machine" is awesome for larger tanks). Make sure the water is of similar ph and temperature and has no chlorine or choramine when you add it to your aquarium.

Remember, goldfish are dirty animals, can grow up to 12 (or more), so house them in an appropriate aquarium for good health and long life. Even if you start out with a ten gallon aquarium, I recommend moving up to a 45-60 gallon aquarium as soon as possible.

Add or subtract many of these points, and your goldfish may have problems. I recommend Wonder Shells (For ph and KH control) or "Medicated Wonder Shells" for prevention and/ or treatment of goldfish disease (ich/ fungus), and water conditions. Of coarse good maintenance, proper feeding, proper filtration, are not replaced by this product. I have used this product on my aquarium maintenance route (27 years experience) with GREAT results.