Guam

The olive flathead gudgeon, Butis amboinensis, is a nocturnal ambush predator from the eastern Indian Ocean to the West Central Pacific. It inhabits brackish estuaries, lagoons and mangroves, entering tidal freshwater rivers to an extent, and often aligns itself with solid surfaces or swims upside-down. It is occasionally exported as bycatch and differs from congeners in lacking enlarged outer teeth and scales on the cheek. It is territorial and should probably be kept singly.

Stiphodon percnopterygionus is a small stream-dwelling goby ranging from southern Taiwan through the Ryukyu and Bonin islands to Guam and Palau. Rare in the aquarium trade, it is among the most easily identified in the genus. Males have highly extended fourth and fifth spines in the first dorsal fin, and adults reach only 30-35 mm SL. Like other Stiphodon it is a specialised algal grazer with an amphidromous life cycle.

The green swordtail, Xiphophorus hellerii, is a livebearer native to southeastern Mexico, Guatemala, Belize and Honduras. Among the world's most recognisable aquarium fishes, it is ubiquitous in the trade, where selective breeding and hybridisation with X. maculatus and X. variatus have produced a bewildering array of ornamental forms. The name is often misspelled X. helleri.