Pond Depth

Ideally koi, ghost carp, and other large fish need a depth of at least 91 cm (3 feet) in the deepest part of the pond to allow these fish, which can grow to over 61 cm (2 feet) in length, to over winter successfully. Smaller fish such as goldfish, shubunkins and sarasa comets can be housed in smaller ponds, with a minimum depth of 46 cm (18 inches).

It is helpful in maintaining a healthy and balanced pond to have at least 40% of the pond area at the maximum desired depth. This will reduce the likelihood of temperature fluctuations which can encourage algae growth and be harmful to fish health.

Tips on depth

9I cm (3 feet) or more for larger fish.
46cm (18in) or more for smaller fish.
At least 40% of the area at maximum depth.
The deeper the pond – the better for pond balance.