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.
Killifish
Many killifish are lavishly coloured; and most species are easy to keep and breed in an aquarium. Specimens can be obtained from specialist societies and associations. Striped panchax (aka. Golden Wonder Killifish) are commonly found in pet shops, but caution must be exercised when considering tank mates, since the mouth of the Striped panchax is as wide as the head, and much smaller fish will be eaten. Flagfish, native to south Florida, is another species of killifish commonly found in pet stores. They are useful in aquariums for algae control. The Golden topminnow ("Fundulus chrysotus") is also native to the United States and often available at auction, but care must be taken with these fish – and the Golden Wonder – to stop them from jumping out of the tank. A firm cover and a layer of floating plants is best when keeping these fish.