The domestic Goldfish is one of the most popular fish kept today, and also one of the very first to be kept indoors. Contrary to dated belief, goldfish cannot be kept in tiny, unfiltered bowls. They should get quite large (about the size of a sweet potato) and live for decades. These are intelligent fish that will come to recognize their owners; the idea that their memory span is only 3 minutes has been disproven by multiple scientific studies. An ideal environment for goldfish is a 30-40 gallon tank with at least 2-3 goldfish, and nice strong filtration.

Ranchuare one of the breeds of goldfish with distinctive fleshy hoods or wen. They have an egg shaped body and a double tail. Thesecalico ranchu are a bluish white base colour with black and orange splotching. These individuals are around 2-3 long in the body.