Cold water fish can be appropriate for tanks and ponds, but are also found in the world's oceans. These fish prefer a habitat that is 10 to 23.9 degrees Celsius. The temperature may not seem cold and is more along the lines of room temperature. Marine scientists around the world are finding that cold water fish are being affected by climate change, thus a significant decrease in population of natural habitats could occur.
The cold water koi, while beautiful, have the ability to survive freezing conditions. These fish can grow up to one to two feet in length. Koi can also be potentially worth thousands of dollars. Their natural habitat is a pond. Good fung shui, or luck in Chinese culture, is what koi is known for. When raising a pond of koi, as the fish gain your trust, you will be able to hand-feed them.
Atlantic Bluefin Tuna
This metallic blue cold water fish, on average is 6.5 feet long and weighs 249 Kilogram. Atlantic bluefin tuna are warm blooded, but enjoy a natural cold water habitat. Unfortunately, they are quite popular as sushi and their numbers have been driven considerably low due to human consumption. This cold water fish can travel up to 43 miles per hour. Their diet includes small fish, squid and plankton and even kelp.
Goldfish have been kept as pets for over 1,000 years, with the oldest living goldfish at 43 years old. Unfortunately, goldfish aren't as hardy as they once were due to over-breeding; they can't handle the water quality of some unfiltered bowls and aquariums. However, these cold water fish can survive the freezing temperatures of an outdoor pond and grow to fill their space. This is why goldfish in ponds are large, compared to those in a smaller aquarium.
The cold water anchovy isn't just a pizza topping. As a salt water forage fish, they are small and green and blue in colour. Found in many of the world's oceans, there are 140 different anchovy species and they live in large schools. The anchovy can grow to be 2 centimetres (0.79 inches) to 40 centimetres (15.7 inches) in length. A significant food source for every predator in its environment, the anchovy can also be found in Caesar salad and Worcestershire Sauce.