Anguillicola crassus
Nematoda» Nematoda» Secernentea» Spirurida» Anguillicolidae» Anguillicola crassus
This is a parasite nematode often 3cm in length that can only be noticed by opening up the body cavity of the freshwater eel. It has a large girth and a transparent outer skin that allows the inner organs to be seen. ...
Aphanomyces astaci
Chromista» Oomycota» Oomycetes» Saprolegniales» Leptolegniaceae» Aphanomyces astaci
This Oomycete pseudofungus is the aetiologic agent for the disease which is known as crayfish plague. Crayfish plague is a disease which, as an acute disease, has only created problems in Europe, not in the native range of North America where crayfis...
Cercopagis pengoi
Crustacea» Arthropoda» Branchiopoda» Diplostraca» Cercopagididae» Cercopagis pengoi
A water flea with body size up to 2 mm and caudal process with length up to 10 mm. The head is essentially composed of a large single eye, where the amount of black pigment makes less than one half of the diameter of the eye. Parthenogenic females of...
Corbicula fluminea
Mollusca» Mollusca» Bivalvia» Veneroida» Corbiculidae» Corbicula fluminea
Inland water filter feeding bivalve with a globular shell. Has the capability of collecting food in sediments with its extendable foot. It has tan to brown, ridged solid shells. They occur in large numbers in sediments and are usually <3cm. In Europ...
Cordylophora caspia
Cnidaria» Cnidaria» Hydrozoa» Hydroida» Clavidae» Cordylophora caspia
This colonial hydroid (up to 10 cm high) light brown in colour occurs in brackish waters, branching occasionally from alternate sides. Branches are ringed at the base and have terminal polyps with colourless, extensile tentacles that are 12-16 long. ...
Crassula helmsii
Magnoliophyta» Magnoliophyta» Rosopsida» Saxifragales» Crassulaceae» Crassula helmsii
A small succulent flowering perennial that grows rapidly to form an extensive lush-green "carpet" that floats on freshwater or may be submerged. Growth can extend from margins of sheltered waterbodies to completely cover the water surface with tangle...
Dikerogammarus villosus
Crustacea» Arthropoda» Malacostraca» Amphipoda» Gammaridae» Dikerogammarus villosus
The killer shrimp is an omnivorous predator. It can feed on a variety of macroinvertebrates, including other gammarid species, and exhibits an important biotic potential and ecological plasticity. ...
Dreissena polymorpha
Mollusca» Mollusca» Bivalvia» Veneroida» Dreissenidae» Dreissena polymorpha
Sessile bivalve mollusc, forming dense colonies on various hard substrates in fresh and slightly brackish waters. It has brownish-yellowish triangular shells (up to 50 mm) with dark and light coloured ("zebra") zigzag banding. It is a filter feeder o...
Elodea canadensis
Magnoliophyta» Magnoliophyta» Liliopsida» Alismatales» Hydrocharitaceae» Elodea canadensis
It is an aquatic herb with branching stems 20-30 cm long, which tends to form dense monospecific stands that can cover hundreds of acres. Leaves are oblong-linear in groups of three. Flowers are white or pale purple appear at the water surface. Fruit...
Eriocheir sinensis
Crustacea» Arthropoda» Malacostraca» Decapoda» Varunidae» Eriocheir sinensis
This small crab has a carapax that might may reach 5 cm and are usually brownish in colour. A characteristic feature is the mitten like "fur" on the claws. The Chinese mitten crab is an omnivorous predator. The diet of the crabs includes a wide range...
Gyrodactylus salaris
Platyhelminthes» Platyhelminthes» Trematoda» Monopisthocotylea» Gyrodactylidae» Gyrodactylus salaris
This is a very small worm parasite (<1mm) which attaches to the outer body and gills of fish in the salmon family. It damages the skin and this can lead to infections. Unless heavily infested, it is unlikely that its presence will be noticed. There ...
Mnemiopsis leidyi
Ectoprocta» Ctenophora» Tentaculata» Lobata» Bolinopsidae» Mnemiopsis leidyi
A comb jelly, length up to 100 mm. The body is laterally compressed, it has four rows of small ciliated combs which are iridescent by day and may glow green by night. The colour is usually transparent or slightly milky and translucent. Feeds on holop...
Neogobius melanostomus
Osteichthyes» Chordata» Actinopterygii» Perciformes» Gobiidae» Neogobius melanostomus
It is a small, soft-bodied fish, with a fused pelvic fin that forms a suction disk on the ventral surface. The body is brownish grey with dark brown lateral spots. Mature males are completely black during spawning and nest guarding, with yellowish sp...
Procambarus clarkii
Crustacea» Arthropoda» Malacostraca» Decapoda» Cambaridae» Procambarus clarkii
Crayfish with total body length (TL) up to 15 cm. Adults are usually dark red, orange, or reddish brown. Chelae are red on both surfaces, typically S-shaped and covered in spines and tubercles. Females have the seminal receptacle located between base...
Pseudorasbora parva
Osteichthyes» Chordata» Actinopterygii» Cypriniformes» Cyprinidae» Pseudorasbora parva
This zooplanktivorous fish has an elongated body, slightly flattened on sides, resembling that of the species of the genus Gobio. Maximum size up to 110 mm, though most individuals are 80-90 mm in length and 17.1-19.2 g in body mass. The color...
Salvelinus fontinalis
Osteichthyes» Chordata» Actinopterygii» Salmoniformes» Salmonidae» Salvelinus fontinalis
This salmonid predatory fish has a long, streamlined body with a large mouth that extends past the eye. Colour variations include olive, blue-grey, or black above with a silvery white belly and wormlike markings (vermiculations) along the back. They ...