qu ila ▁is ▁en demic ▁to ▁the ▁Am eca ▁River ▁bas in ▁in ▁west - central ▁Mexico . ▁Its ▁current ▁distribution ▁is ▁restricted ▁to ▁a ▁single ▁spring ▁pool ▁in ▁Te uch it lán , ▁only ▁ ▁in ▁diameter , ▁where ▁a ▁population ▁consisting ▁of ▁less ▁than ▁ 5 0 ▁adult ▁fish ▁live . ▁Even ▁in ▁this ▁habitat , ▁it ▁is ▁out number ed ▁by ▁introduced ▁gu pp ies ▁by ▁a ▁factor ▁of ▁six . ▁Before ▁the ▁discovery ▁of ▁the ▁pool ▁population ▁in ▁ 2 0 0 0 / 2 0 0 1 , ▁Zo og on etic us ▁te qu ila ▁was ▁generally ▁thought ▁to ▁inhab it ▁rivers ; ▁however , ▁no ▁fish ▁could ▁be ▁found ▁in ▁the ▁original ▁habitat ▁and ▁the ▁species ▁was ▁considered ▁ext inct ▁in ▁the ▁wild . ▁Int rodu ced ▁fish ▁species ▁have ▁been ▁imp licated ▁in ▁the ▁disapp earance ▁of ▁Zo og on etic us ▁te qu ila ▁from ▁its ▁type ▁local ity . ▁Hab itat ▁d eter ior ation ▁may ▁also ▁have ▁contributed . ▁Pol l ution ▁and ▁water ▁extra ction ▁are ▁thre ats ▁to ▁the ▁pool ▁where ▁the ▁wild ▁population ▁pers ists . ▁Capt ive ▁populations ▁are ▁maintained ▁by ▁aqu ar ists . ▁ ▁Description ▁Al ong ▁with ▁other ▁Mexican ▁go ode ids , ▁Zo og on etic us ▁te qu ila ▁are ▁viv ip ar ous ; ▁this ▁led ▁the ▁genus ▁to ▁be ▁originally ▁included ▁in ▁family ▁Po ec ili idae . ▁Cl utch ▁size ▁is ▁up ▁to ▁ 2 9 ▁young . ▁M ales