If you don't want to heat up your aquarium, creating a cold water fish tank might be ideal for your home. Cold water fish, for aquariums and ponds, refers to fish species that can live in water temperatures below 68 degrees Fahrenheit. These cold water fish usually grow at a slower pace than types that require warm temperatures (except for the koi and goldfish). The most popular cold water fish are the koi and goldfish.
Goldfish are a popular cold water fish. They come in many different colors including white, orange, black and gray. There are two main body shapes of goldfish, flat body and round. The flat-body fish is more ideal as a pet for a beginner fish owner. The fish tend to thrive in a community aquarium because they are good swimmers and have a sleeker form, which means they can compete for food. Flat-body goldfish include the common goldfish, comet, shubunkin, wakin and jikin goldfish. The rounder goldfish, depending on the variety, sometimes don't have dorsal fins, which means they're not good swimmers. Fish like the lionhead and ranchu shouldn't be placed in an aquarium with dorsal-finned goldfish, because they will never get anything to eat.
Koi and goldfish were bred from two different species of carp. Koi are often kept in outdoor ponds. Koi have a flatter body than goldfish. Koi can grow large and should not always be confined to an aquarium. An outdoor pool or pond is better for their well-being and happiness. The water should be deep enough that the temperature doesn't fluctuate a lot with the change in weather. Koi can be brightly colored and come in different combinations of orange, yellow, red, white, black or gray.
White cloud mountain minnows are good cold water fish. These fish are small and silver in color, but they also can be golden or yellow. Minnows thrive in cold water conditions, but they may lose color if the water is too cold.
Other Cold Water Fish
Other fish that thrive in cold water aquariums include barbs, shubunkins, sturgeons, Red Shiner and loaches. Larger breeds like gars, catfish and bony tongue fish are more exotic and often found in fresh-water rivers and ponds. The cold water fish react well to various water conditions and temperatures.
Other Cold Water Creatures
For a little variety in your cold water tank, add some other inhabitants to share space with the fish. Other creatures that thrive in cold water tanks include crabs, ghost shrimp, tadpoles, snails and many aquatic plants.