The largest wetland in Europe, witholding one of the widest reed areas in the world, the Danube Delta is dominated by the reed that forms fixed or floating islands. Other numerous species of plants are growing by the riverside and on the floating islands. The sand areas of the Delta are covered with grass and other steppe species: the white willow, the poplar, the Alnus trees, Fraxinus Excelsios, and the mix forests on the sand banks. The water surface is populated by numerous species of plants with floating leaves: the white water lilly, the yellow water lilly, the European frog-bit, the water chestnut, the Common Hornwort.

Fishes: In the Danube Delta there are over 110 species of fishes, among which 75 are fresh water species. An important place among the Danube Delta fishes is reserved to the salt water sturgeons: the Acipenser Stellatus, the Huso huso, from which the caviar is obtained, and  the fresh water sturgeons, the Acipenser ruthenus. Among the migratory fishes, the most important is the Pontic shad. The catfish is the biggest fresh water fish in Romania, the record in the Danube Delta being of 400 kg. For the perch, Stizostedion lucioperca, the record is of 21 kg. Other mostly appreciated fishes are: the pike, the carp, the perch, the bass, the zander, the roach, the bream. On the Danube Delta lakes you can fish the pike, the bass and the carp, the catfish, the perch, etc. On the channels you can catch mostly catfish, carp, perch, bass, etc. The Danube main arms are preferred by the  sturgeons, the carp, the Pontic shad, the catfish, the perch, the pike. The calmer waters are populated by the bass, the German carp, the bream  and the salt waters by the bass, the pike, the flounder, the Mugil chephalus. The marine section is populated by the sturgeons and the Pontic shad.

Birds: in the Danube Delta live over 327 species of birds, representing 81% of the Romanian species of birds. Among these, 218 species nest in the Delta. The aquatic birds are the most numerous: a total of 141 species. In the Danube Delta, the largest pelicans colony in Europe can be found. Along come the pelicans, the egrets, the swans, the cormorants, the herons, the wild ducks and geese, the pigeons,  the swallows, the larks. The aquatic birds are of a few main types: the species that live mainly on the water (the Black-throated Diver, the Great Crested Grebe, the pelicans, the cormorants, some wild ducks), species that live in the reeds ( all the aquatic species), species that live on the shores (the herons, the spoonbills, the glossy ibis), species that live on the meadows bordered with reeds, species that live on the sea coast as well as accessory species, integrated in the aquatic fauna: the River Warbler, the Spotted Flycatcher, the nightingale, the chaffinch, the Great Tit, to which are added, during the nesting period, the ducks, the cormorants and the herons. In the coastal woods, Letea and Caraorman, nest 64 species, typical for these areas ( the Locustella fluviatilis, the blackbirds, the woodpeckers, the Erithacus rubecola, the Parus major, the Sturnus vulgaris, the white-tailed eagle, the Milvus sp., the Aquila sp., the eagle, the pheasant). On the stepped meadows live the Perdix perdix, the Coturnix coturnix, the Skylark). Near to the farms can be frequently found the Collared Dove, the sparrow, the stork. The protected birds in the Danube Delta are: white birds - the white pelican and the dalmatian pelican, the spoonbill, the great white egret and the little egret, the swan, polychromatic birds - the Black-winged Stilt, the Avocet, the shellduck, the ruddy shellduck, the white-tailed eagle. Other species that are followed, in order to be protected, are the Grus grus, and the Danube Falcon. The best periods for bird watching are April-May and June-September. The best places to admire the birds are on the banks of the Danube Delta lakes.

Mammals: the otter, the European mink, the muskrat, the Nyctereutes prociynoides, deers, wild horses, wild cats.

Reptilians: the sands shelter tortoises, vipers, colonies of snakes.