Gambusia affinis in  USM Engineering Campus
Mosquito fish
(source: fishbase, Compiled by SSK)

Gambusia  affinis 
 Family: Poeciliidae , subfamily: Poeciliinae
 Order: Cyprinodontiformes
 Class: Actinopterygii (ray-finned fishes)
 FB name: Mosquitofish
 Max. size: 4.0 cm TL (male/unsexed); 7.0 cm TL (female); max. reported age: 3 years
 Environment: benthopelagic; freshwater; brackish; pH range: 6.0 - 8.0; dH range: 5.0 - 19.0
 Climate: subtropical; 18 - 24°C; 42°N - 26°N
fisheries: minor commercial; aquarium: commercial
 Distribution: North and Central America: Mississippi River basin from central Indiana and Illinois in USA south to Gulf of Mexico and Gulf Slope drainages west to Mexico. One of the species with the widest range of introductions which acquired for itself a near pan-global distribution  Several countries report adverse ecological impact after introduction.
 Diagnosis:  Dorsal spines (total): 0-0; Dorsal softrays (total): 7-9; Anal spines: 0-0; Anal soft-rays: 9-10. Origin of dorsal fin opposite 7th anal ray. Length of anal base much less than half distance from caudal. 8 horizontal scale rows between back and abdomen. Ventrals terminate immediately before anal fin. Pelvics reach ventrals.
 Biology: Most abundant in lower reaches of streams (Ref. 44091). Inhabits standing to slow-flowing water; most common in vegetated ponds and lakes, backwaters and quiet pools of streams. Frequents brackish water. Feeds on zooplankton, small insects and detritus. Used as live food for carnivorous aquarium fishes. Viviparous Effective in mosquito control and widely introduced, but found to compete with indigenous fish and to upset the ecological balance . Viviparous .
 Threatened: Not in IUCN Red List  () ,
 Dangerous: potential pest
 Main Ref: Page, L.M. and B.M. Burr. 1991.