Every year Dacorum Borough Council arrange for Bedwell Fisheries Services to check the condition of the ponds in the borough. This is an extract from their report on three ponds on The Common:

Apostles Pond
This much-visited pond in the woodland is an important part of the local landscape as well as being a very important part of the woodland eco-system. It is a useful watering hole for local wildlife and an important aquatic habitat. This pond contains Crucian Carp and Gudgeon as well as some unwanted ornamental fish (goldfish and shubkins) which have been dumped in the pond.
Over the last few years we have been removing any fish other than native species and I am glad to report that we seem to be winning. A few years ago the Crucian Carp population was failing due to the non-native fish but last year we noticed an increase in the number of carp caught during our fish surveys.
The Apostles Pond is also an important habitat for Common Newts. There are four species of dragon flies present and a large population of water beetles.
Frog Pond
This small pond has remained a quiet corner as it is out of the public eye and seldom visited. It plays an important part in the woodland habitat and has an important population of Rams Horn Water Snails and a good population of dragon flies.
It is important that small ponds like this have some work carried out each year to keep the area round the pond clear and the surface of the pond free from grass growth.

Manor Pond
Another small pond with an important population of Crucian Carp. This small member of the carp family is the only native carp in this country and they are under pressure due to the loss of small ponds and the introduction of other fish species. Dragon flies and Common Newts also inhabit this pond and a small amount of work is needed every year to keep this pond a viable habitat.