How much to feed fish is a common problem. Scientifically, koi and goldfish need 2% of their body weight in food every day when the water is above 10ºC. That equates to 20grams of food per kilo of fish. If it’s difficult to estimate the total weight of fish and so your preferred method is to feed them once or twice a day, use an amount equal to what the fish will consume in 5 or 10 minutes. Between 5 and 10ºC fish still eat but can’t digest protein as well so you should just feed them low protein wheatgerm food when its this temperature. Under 5ºC do not feed the fish. If in doubt it is always better to under feed fish than over feed them. Always.
Check your fish regularly for signs of potential problems or ill health. The first signs can be physical changes such as open wounds or growths, but also watch out for behaviourial changes. If a fish separates itself from the others, clamps its fins close to the body, just hangs at the surface by plants or oxygen sources, or doesn’t eat, attention should be paid to that fish.
From March until November, pumps and filters should be cleaned as often as required which depends on whether they are being used for pond cleanliness or biological purification. Dead foliage should be removed regularly from July to limit the build up of silt and water should be tested regularly if koi are present.
As winter approaches, again excess silt can be removed, the plants should be cut back to the crown so they grow fresh the following spring. Pumps and filters can sometimes be cleaned and switched off.