of fish and invertebrates for coldwater aquariums can be found here.
However, we would recommend cold-water aquarium for the beginners because cold-water fish are much more resistant to water parameter changes.
The defining characteristic of the subtropical aquarium is temperature. Excessively low temperatures (as in a completely unheated aquarium, or outdoors in a pond during the winter) will stress these fish and make them prone to parasites and other diseases. Unlike true coldwater fish, such as goldfish and sunfish, these fish have little resistance to freezing conditions and cannot survive under ice. So while many will do well outdoors during the summer months, they will need to come in once it starts to turn colder in autumn. A minimum of 18°C (64°F) is about right for most of the subtropical species commonly traded.
Though commonly traded, Hong Kong plecos are rarely kept properly, and this has resulted in a reputation for being delicate that isn’t really justified. The average community tank is simply too warm for these fish, and between that and the low oxygen levels, they tend not to live for very long. But when kept at subtropical temperatures, and with extra aeration in the summer to keep the oxygen concentration high, these fish do well. They are not picky about pH or hardness, but good filtration is essential. While Hong Kong plecos are sometimes kept in coldwater aquaria they actually do best in heated aquaria kept at a temperature of around 20°C (68°F).
Coldwater Fish Species for Your Freshwater Aquarium - Pinterest
Freshwater Frenzy: Best Fish for a Cold-Water Aquarium.
When it comes to unheated or coldwater aquariums, most aquarists only think of goldfish setups. However, there are actually many options for low-tech tanks that don’t even require a heater. Popular dwarf shrimp like cherry shrimp can actually be kept in unheated aquariums, and the same goes for some popular fish species like .Goldfish: Goldfish are, perhaps, the no-brainer choice when it comes to raising fish. The popularity of the goldfish may have something to do with their portrayal in movies and television. Do not worry, though; this does not make raising goldfish any more difficult than it should be! This low maintenance fish for coldwater aquariums is fun to raise. You will often see it swimming around vigorously, given that it is kept healthy. To do so, make sure to keep the water temperature below 22 degrees Celsius (72 in Fahrenheit)—the ideal temperature for goldfish is from 65 to 65 degrees Celsius. Otherwise, it may suffer from lack of oxygen. Furthermore, this low maintenance coldwater aquarium fish can eat messily, so keep the aquarium clean.Top Tip: Tip: Because of the differences in temperature ranges Coldwater and freshwater fish are not typically mixed. However, many of the Coldwater species listed above, Barbs for example can do very well in both Coldwater and tropical aquariums.Chinese Danio: The Chinese Danio, otherwise known as the White Cloud Mountain Minnow, is one of the best choices for beginners. This is because it requires little maintenance, can adapt to various conditions, and is suitable for unheated freshwater aquariums. Similar to the goldfish and tetra, these low maintenance coldwater aquarium fish are social creatures—when they interact with tankmates, they are more likely to develop their luster. Speaking of which, White Cloud Mountain Minnows typically exhibit numerous colors when healthy and happy. Their males are more colorful than the females. Make sure not to keep Chinese Danio with larger, predatory fish to keep them away from trouble.