Transgenic GloFish have gone on sale in aquatic stores in Chicago, according to the Chicago Sunday Times.
The transgenic Zebra danios, contain a gene from a jellyfish or coral which causes them to fluoresce under certain lighting conditions.
The fish are selling for between $7.99 and $11.99 - an unmodified, natural form of the Zebra danio sells in the UK for about 1.00.
Sean Bailey, owner of Aquatic World told the paper: "They're really selling."
Others think that the craze will soon pass.
The state of California recently banned the sale of the genetically modified fish, and they are yet to arrive in the UK. The Ornamental Aquatic Trade Association has issued a statement to their members regarding their position on the sale of GM fish.