Coldwater fish can have different meanings in different contexts. In the context of aquariums, it refers to fish species that do not require a heater to remain within tolerable temperatures in a typical indoor aquarium. However, most or all ornamental fish species are able to tolerate temperatures as low as or lower than room temperature, with most stenothermic tropical species having critical thermal minimums of around 10-12 °C. Although these fish are capable of surviving in unheated aquaria, their temperature preferences may vary. For example, koi, goldfish, and pond loaches are commonly considered to be cold-water fish because of their ability to survive at very low temperatures, but their temperature preferences and/or physiological optimal temperatures are 32 °C (90 °F), 24-31 °C (75-88 °F), and 26-28 °C (79-82 °F), respectively. Because many of the ornamental fish considered to be “coldwater fish” are more accurately eurythermal fish and many prefer temperatures similar to, or even warmer than those preferred by certain tropical fish, the term “coldwater fish” in the aquarium context often misleads pet owners into keeping fish below their preferred temperature. Anglers also may loosely break down fish into categories of warm-water fish, cool-water fish, and cold-water fish. Warm-water fish are species that tend to dwell in relatively warm water, and in North America include species such as largemouth bass, sunfish, and bullhead catfish. Cool-water species, such as smallmouth bass and walleye, can tolerate a wide range of temperatures, but tend to be most abundant in cooler rivers or deeper parts of ponds and lakes. Cold-water species, such as char, trout, salmon, grayling, and burbot become stressed at high temperatures and are most active in cold water. Because these designations are informal, different authorities may recognize different boundaries in temperature preference between the categories. Freshwater aquarium fish Southern redbelly dace Lepomis Shubunkin Comet goldfish Common goldfish Fancy goldfish Black telescope Fantail goldfish Oranda Ryukin Weather loach White Cloud Mountain minnow Celestial Pearl Danio Buenos Aires tetra Gold barb Rosy barb Odessa barb Fathead minnow Banded corydoras Chinese high fin banded shark Three-spined stickleback Ticto barb Pygmy sunfish Enneacanthus Texas cichlid Paradise fish Green barb Zebra danio Bengal danio Leopard danio Danio tinwini Bulldog pleco Rhinogobius Desert goby Highland swordtail (Xiphophorus malinche) Japanese ricefish Zacco Black lined loach (Yasuhikotakia nigrolineata) Red shiner (Cyprinella lutrensis) Spotted gar Longnose gar Rosy red minnow Hillstream loach Spined loach Stone loach Common minnow Vietnamese cardinal