Animal Species:Stout Floater, Schindleria brevipinguis Watson & Walker, 2004
The recently described Stout Floater is arguably the world's smallest (and lightest) vertebrate species. All six specimens collected so far have been found in depths of 15 m to 30 m in coral-reef lagoons in the vicinity of Lizard Island, Great Barrier Reef, Australia.
Standard Common Name
Stout Infantfish. Fishes in the family Schindleriidae are often called Schindler's fishes.
The recently described Stout Floater is arguably the world's smallest (and lightest) vertebrate species. The species is paedomorphic, which means that adults retain larval characters. It is an elongate fish with large eyes and a well developed caudal fin. With the exception of the eyes, this fish lacks pigmentation, and is transparent in life.
The species name, brevipinguis, comes from the Latin brevis, meaning short (refers to the small size of the species) and pinguis meaning stout (refers to the deeper, broader body of this species compared with other species in the genus).
The Family Schindleriidae, which is related to gobies (Johnson & Brothers, 1993), contains tiny fishes that live in and near coral reefs. They may be the most abundant coral-reef fishes in the world, reaching abundances of seven per cubic metre in waters near reefs (Leis, 1978).
The largest specimen captured to date is a gravid female that is 8.4 mm in standard length and weighs about 1 mg (one millionth of a kilogram).
Only two other species of infantfishes are currently known, S. praematura and S. pietschmanni. The Stout Floater differs from the other species of infantfishes by having a deeper body, fewer dorsal and anal fin rays and larger eyes. The urogenital papilla of males differs in shape from those of other Schindleria species.
All six specimens collected in the vicinity of Lizard Island, Great Barrier Reef, Australia. It is likely that the Stout Floater is more widely distributed. The first specimen was collected in 1979 by Jeff Leis during fieldwork based at the Australian Museum's Lizard Island Research Station. Since then, another five specimens have been collected by Jeff Leis. All six were used in the description of the new species.
The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums. Click on the map for detailed information. Source: Atlas of Living Australia.
Distribution by collection data
The specimens have been collected from depths of 15 m to 30 m in coral-reef lagoons.
Very little is known of Stout Floater biology. Females reach sexual maturity by 7 mm to 8 mm in length and males mature by 6.5 mm to 7 mm. A recent paper by Kon and Yoshino (2002), based on otolith rings, showed that infantfishes are very short-lived. In the Ruykyus Islands, Japan, they reach maturity in 23 to 60 days.
- Hoese, D.F., Bray, D.J., Paxton, J.R. & G.R. Allen. 2006. Fishes. In Beesley, P.L. & A. Wells. (eds) Zoological Catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia. parts 1-3, pages 1-2178.
- Johnson, G.D. & E.B. Brothers. 1993. Schindleria: a paedomorphic goby (Teleostei: Gobioidei). Bulletin of Marine Science. 52(1): 441-471.
- Kon, T. & T. Yoshino. 2002. Extremely early maturity found in Okinawan gobioid fishes. Ichthyological Research. (49): 224-228.
- Leis, J.M. 1978 Distributional Ecology of Ichthyoplankton and Invertebrate Macrozooplankton in the Vicinity of a Hawaiian Coastal Power Plant. PhD Thesis. University of Hawaii. Pp. 317.
- Watson, W. & H.J. Walker Jr. 2004. The world's smallest vertebrate, Schindleria brevipinguis, a new paedomorphic species in the family Schindleriidae (Perciformes: Gobioidei). Records of the Australian Museum. 56(2): 139-142.
Mark McGrouther , Senior Fellow