''Butis koilomatodon'', commonly known as the mudsleeper, is a species of fish in the family

Butidae Butidae is a family of sleeper gobies in the order Gobiiformes. The family was formerly classified as a subfamily of the Eleotridae but the 5th Edition of Fishes of the World classifies it as a family in its own right. Molecular phylogenetic anal ...

native to fresh,

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

and salt water of the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

region, ranging from Madagascar and Mozambique to the Philippines, China and Australia. It has been introduced to the Atlantic region where considered invasive and known from Panama, Venezuela and Brazil as well as Nigeria. This predatory species mainly lives in rivers,

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

and

mangrove A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...

s, and reaches up to in total length.

Introduction to Brazil

''B. koilomatodon'' are expanding their range to the southwestern Atlantic along the coast of Brazil. It has been found on the eastern coast of Brazil, in 1989, but was not identified until 2000. As of the summer of 2012, 23 specimens of ''B. koilomatodon'' have been collected along the coast of Brazil, all specimens were collected at six different locations along the coast. Biologists have been able to identify 17 of the specimens as male, four as female, and two more were not able to be sexed. And many of the specimens were in different stages of maturity, a breeding population is likely to be established, but enough data are collected to conclude it finally. How this species got to the other side of the continent of South America is unclear. Many believe they were brought over in the ballast tanks of ships. The small size of the species makes it very easy for them to enter the intake holes on a ship's ballast tank. Also, their ability to tolerate a wide range of salinity levels, as well as temperature fluctuations, makes it likely for them to inhabit a

ballast tank A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, ...

on journeys across the ocean.

References

{{Taxonbar, from=Q2490030 Fish of China Fauna of Rivers State Fish described in 1849 koilomatodon