Freshwater Jellyfish

The freshwater jellyfish (Craspedacusta sowerbyi) is a very small jellyfish used in aquarium hobby tanks.

Native Range
The freshwater jellyfish is native to the Yangtze river valley in southern China. [1]

North America
The freshwater jellyfish can be found as far north as the border between Ontario and Quebec in Canada and New York state in the United States of America. [2]

Within the USA, the freshwater jellyfish is widespread, with the largest populations in the eastern half of the country, especially towards the north-east. They are also present on the Hawaiian island of Mua'i. [3]

It is also present in the states of Nuevo Leon and Sinaloa in Mexico. [3]

Central America
The freshwater jellyfish has been seen in Guatemala as well as at a tributary to the Panama Canal. [8]

South America
This species is thought to be present in many parts of South America. [3/6] It is known to be present in parts of Brazil. [4]

Oceania
The freshwater jellyfish is present in much of Australia ([8]) especially to the south-west and south-east. [5] They are also present in New Zealand. [7/8]

These jellyfish have also been seen in Guam. [8]

Asia
The freshwater jellyfish seems to be most prevelent in Asia in the south-east. They have been found in the state of Sarawak in Malaysia, in north-east Thailand and in Laos. It is also present in Hyago Prefecture in south Japan and south Taiwan. [8]

These jellyfish are also present in west and north India, Iraq and Israel. [8]

Africa

Freshwater jellyfish have also been sighted on the Zambezi river between Zambia and Zimbabwe, west Mozambique, north-east Botswana and southern, eastern and northern South Africa (9). [8]

Europe
The freshwater jellyfish has been recorded in Kalininskiy District in west Russia. It has also been seen in south-west Poland, throughout Slovakia, in south-west Bulgaria, throughout Serbia, west Romania, throughout Austria, north and west Italy, throughout Germany, throughout the Netherlands, south-east Belgium, throughout France throughout England, south Wales & even east Scotland in the UK, throughout Spain and the southern half of Portugal. [8]

It has also been recorded in Finland, Sweden and Lithuania. [1]

The freshwater jellyfish is also present in Cyprus. [8]

Pathways and Introduction
The freshwater jellyfish is porbably transported in its larval stage, when it is very difficult to notice, or even microscopic. It may then be brought to new countries with other aquatic species. [1/3]

This species was originally described in water-lily tanks in Regent's Park, London, outside of it's native range. It was first recorded on the European mainland in France in 1901. [1]

These jellyfish were first seen in Guam in 1970. [3]

Impacts
It is thought that freshwater jellyfish may affect the zooplantonic structure, as they prefer to prey on larger zooplankton. There are also fears that they could predate fish larvae and eggs, although this theory is sometimes disputed. [3]

It has also been speculated that these jellyfish could reduce the oxygen content of the water during population explosions. [1]

Control and Removal Methods
Since invasive population explosions are erratic and rare ([1]), this species is not considered a notable invasive concern and so no control methods have been put in place. [1/3]