Wild life(fish & birds) in the Moats and New Purification System

There are approximately 17 kinds of fish living in the moats;
The following are examples of fish found in the moats.
Japanese natives : Carp(Cyprinus psecies), Crusian Carp(Carassius species), Stone Moroko(Psedorasbora parva), Japanese Smelt(Hypomesus trans-pacificus f.Nipponensis), and Common Freshwater Goby(Phinogobius bruneus), etc.
Chinese natives : Grass Carp(Ctenopharyngodon idella), Silver Bighead(Hypophthalmichthys molitri), etc.
American natives : Large Mouth Bass(Micropterus salmoides), Bluegil(Lepomis macrochirus).
Habitat of wild birds ; The following is an example of birds which inhabtat the moats throughout the year, Spot-Billed Duck(Anas poecilorhyncha), Great Comorant(Phalacrocorax carbo), Little Egret(Egretta garzaatta), Chinese Little Grebe(Podiceps ruficollis v.poggei), etc.
In the winter migratory birds such as the following may be seen ; Tufted Duck(Aythya fuligula), Mandarin Duck(Aix galericurata), Eurasian Wigeon(Anas ponelope), Northern Shoveler(Anas clypeata), Kamchatkan Black-Headed Gull(Larus ridibundus 'Sibiricus'), etc.
These moats are the most important fresh water habitat for wild life in central Tokyo. However rainwater accounts for over 90% of the moats water and because there is no natural flow in the moats the quality has steadily deteriorated, and this is especially evident in the summer.
In 1995, the Environment Agency completed the construction of a large water purification system close to the moats to help improve the water quality, and already significant improvements have been made in the water quality since the purification system went into operation.