There are many things to consider when constructing a pond for crayfish. The first think is to decide whether or not you want to keep fish as well, that’s the sort with scales. If you do decide to have a pond to keep both crayfish and say goldfish then the pond needs to be built at different depths. Goldfish will require deep water to remain cool in the heat of the summer whilst crayfish are usually found in the shallows. Therefore a pond with different depths ranging from very shallow to deep is required. The pond should be shallow all around the edges this will also be an additional safeguard if you have small children in the household.
Crayfish can live in little caves on the river bank so you might consider making holes in the pond banks just below the water line. The holes should be about six to ten inches deep and about six inches in diameter. The more crevices you build into the pond the better as crayfish are shy creatures and don’t like to make their presence felt. This will also be a refuge too for tiny goldfish when they first hatch.
The bottom of the pond will need some sort of medium for the crayfish like sand and gravel. They will use the pond bed to hide from predators real or imagined. The substrate should be about ten inches to a foot deep. Large pebbles are a good idea too as crayfish can hide between the gaps when threatened.
A pond for crayfish should also have plenty of water plants. Irises and water lilies are fine and will also be a refuge for small goldfish when young. However, more importantly there should be plenty of free standing surface weed especially in the shallows. Crayfish love to hide in surface weed and might also find much of their natural diet in amongst the aquatic plant life.
After importing crayfish they will most likely all to ground. You might wonder where are in your pond. The most telling of signs is air bubbles rising from the bottom. All ponds have a certain amount of air bubbles rising from the gravel below when it is disturbed. The thing is to stop and study the air bubbles and see if they are on the move, if so they are certainly made by a crayfish foraging down in the depths of your pond.