Goldfish
The goldfish ("Carassius auratus") is a freshwater fish in the family Cyprinidae of order Cypriniformes. It is one of the most commonly kept aquarium fish.
Common goldfish
Goldfish diets can be a range of pellets, flakes, boiled soft vegetables, and blood worms. Overfeeding can result in throwing off their biological balance, increasing the risks of diseases. The common goldfish should be fed “a small pinch of food two or three times a day…” to prevent extraneous amounts of food dirtying the water; this will also depend on the size of the fish of knowing to feed the fish more or less to keep healthy. Filtration will help prevent the bowl from getting dirty more quickly. A filtration system also helps produce good bacteria for the fish to make the water at safe levels. There are different types of filtration systems, ranging from the store bought external or internal filters or the use of aquatic plants. The reason a filtration system becomes helpful is due to keeping the nitrate levels low; ammonia is introduced in the water when the fish excretes which develops into nitrite into nitrate, leading into possible nitrate poisoning.