Fish, whether koi or goldfish, make an excellent addition to the garden pond. Here are a few things to remember if you are planning to have pond fish.
GOLDFISH (Carassius auratus) – Originated in China before 1000 AD. Years of selective breeding have produced the many of varieties goldfish available today. Common goldfish like sarasa comets and shubunkins are able to tolerate temperature from 0-32 C (32-90 F). The fancy varieties of goldfish such as fantails, orandas, and ryukins prefer temperatures from 13-32 C (55-90 F) and therefore are not as well suited to spending the winter outdoors. However several of our customers overwinter them in their ponds with success. Their maximum size (35-40 cm / 14-16 in) but they rarely grow to that length. they stay considerably less than koi, which makes goldfish a better choice if you have a small pond.
KOI (Cyprinis carpio) – Modern koi varieties originated in Japan. There are 14 classifications of colour pattern of koi. Like goldfish, koi can tolerate temperature from 0- 32 C (32-90 F). Small koi are suitable for most ponds, but one must keep in mind that they can reach lengths of 90 cm (36 in) or more. Even at half this size, koi can cause many problems by constantly stirring up detritus and silt from the bottom, and eating soft new plant growth in a well planted pond.
ORFE (Leuciscus idus) – Originating in Europe where they are found in lakes and slow moving rivers, the most common type for ponds is the golden form, the golden orfe. These fish are quite active, and grow quite rapidly, but they can be somewhat shy unless they are kept in small schools of 6 or more. The orfe can reach a maximum length of 45-60 cm (18-24″), so it may outgrow small ponds.
MOSQUITO FISH (Gambusia affinis)- The mosquito fish is a small and, grey fish with a rounded tail and a upward-pointing mouth adapted for feeding at the water’s surface. closely resembling guppies, which belong to the same family. The females don’t lay eggs, but are live bearing, producing broods as large as 60 to 100 young. Females are larger than males reaching length of 7 cm (2.5″), while males reach only 4 cm (1.5″).
It is best to introduce fish into your pond gradually. Add no more than 5 or 6 small fish at one time to allow your pond to achieve a natural balance and prevent an ammonia build up. In ponds with adequate circulation and filtration, a maximum stocking density of 1-2 inches of fish per 10 square foot of surface area is acceptable. If your pond becomes too crowded with fish , the water quality begins to decline. The result is elevated levels of ammonia, nitrite, nitrates and phosphate. this stresses any pond fish and usually leads to disease.
Here is another general guideline for how many inches of pond fish you can stock in a well filtered pond.
Of course this value can change depending on amount of plants in the pond, whether a biological filter is used, the depth of the pond, and many other factors. When purchasing fish, remember to leave plenty of room for your fish to grow and thrive in your pond.
The amount of feed and type of fish food depends on the season, more directly on the water temperature. Being cold blooded, a fishes body temperature depends directly on the water temperature. The warmer the water, the higher the fish’s metabolic rate and vice versa. The same is true for the bacteria that live in the fish’s digestive system and break down their food. These bacteria become inactive at about 46°F or 8°C, therefore you should not feed your fish when the water temperature drops much below 50°C. Goldfish and Koi have delicate digestive systems, it is best to feed them only what will be eaten in a few minutes 2-4 times a day, rather than letting them gorge once a day.