Coldwater Freshwater Fish
These fish can be kept in unheated tanks, and originate from the rivers and streams of Europe and the Far East. These were the first fish to be raised in captivity by humans, primarily for food. In view of this, people have been keeping coldwater freshwater species longer than any other. Because these fish don't require heat, it gives them the advantage of being an outdoor fish. They can be kept in ponds, which is especially good if your fish were to outgrow their tank. Despite not requiring heat, it is still important to regulate the temperature of the water, especially in the summer, because as the water heats the oxygen level will decrease. The drawback to keeping coldwater freshwater species is that they can grow very large, and require much more space than their warmer-blooded counterparts.
The two main species of coldwater fish common in fishkeeping are goldfish and Koi, but there are other species as well.
Goldfish
Common Goldfish
Size: Up to 200mm long
Origin: China
Swimming Level: All levels
Water Temperature: 0-20C
Feeding Requirements: All foods
Bristol Shubunkin
Size: Up to 125mm long
Origin: China
Swimming Level: All levels
Water Temperature: 0-20C
Feeding Requirements: All foods
Comet
Size: 110mm long
Origin: China
Swimming Level: All levels
Water Temperature: 8-20C
Feeding Requirements: All foods
Fantail
Size: 90mm long
Origin: China
Swimming Level: All levels
Water Temperature: 8-20C
Feeding Requirements: All foods
Veiltail
Size: Up to 90mm long
Origin: China
Swimming Level: All levels
Water Temperature: 8-20C
Feeding Requirements: All foods
Telescopic Moor
Size: Up to 120mm long
Origin: China
Swimming Level: All levels
Water Temperature: 8-20C
Feeding Requirements: All foods
Oranda
Size: Up to 120mm long
Origin: China
Swimming Level: All levels
Water Temperature: 8-20C
Feeding Requirements: All foods
Celestial
Size: Up to 110mm long
Origin: China
Swimming Level: All levels
Water Temperature: 8-22C
Feeding Requirements: All foods
Lionhead
Size: Up to 120mm long
Origin: China
Swimming Level: All levels
Water Temperature: 8-22C
Feeding Requirements: All foods
Ranchu
Size:150mm long
Origin: Japan
Swimming Level: All levels
Water Temperature:18-22C
Feeding Requirements: All foods
Ryukins
Size: Up to 260mm long
Origin: Japan
Swimming Level: All levels
Water Temperature:18-22C
Feeding Requirements: All foods
Koi
Scientifically speaking, Koi is a form of carp (Cyprinus carpio). Koi have similar bodies to goldfish, although they grow much larger and have a single barbel at the corners of the mouth. They are seen in single colours, two-colour and fully variegated. koi's scales can differ greatly - some have a few large scales, or raised scales, like a pine-cone, and some have a kind of metallic flecking. Some specimens can reach a metre in length if carefully nurtured. If you have indoor koi, they really must be moved to an outdoor pond when they reach about 120mm long. Check the depth of your pond if it is winter - you will need at least 2 metres of depth so the koi can be safe from icing.
Hariwaki & Kohaku Koi (two-colour)
Size: Up to 250mm (juvenile)
Origin: Japan
Swimming Levels: All levels
Water Temperature: 0-20C
Feeding Requirements: All foods
Asagi & Taisho Sanke ( three-colour)
Size: Up to 250mm (juvenile)
Origin: Japan
Swimming Levels: All levels
Water Temperature: 0-20C
Feeding Requirements: All foods
Mongrel Koi
Size: Up to 250mm (juvenile)
Origin: Japan
Swimming Levels: All levels
Water Temperature: 0-20C
Feeding Requirements: All foods
Other Coldwater Species
Pale Chub
Size: 180mm long
Origin: Far East
Swimming Levels: All levels
Water Temperature: 8-20C
Feeding Requirements: All foods, algae
Pumpkinseed
Size: 200mm long
Origin: North America
Swimming Levels: All levels
Water Temperature: 8-22C
Feeding Requirements: All foods
Bitterling
Size: 90mm long
Origin: Europe
Swimming Levels: All levels
Water Temperature: 10-22C
Feeding Requirements: All foods
Pygmy Sunfish
Size: 37mm long
Origin: Florida
Swimming Levels: All levels
Water Temperature: 10-22C
Feeding Requirements: All foods, worms
