▁be ▁vertical ▁bars ▁on ▁the ▁sides ▁that ▁are ▁thin , ▁w avy , ▁and ▁sil very . ▁Colors ▁are ▁more ▁inten se ▁in ▁males ▁during ▁the ▁re product ive ▁season , ▁as ▁they ▁become ▁dark ▁o live - green ▁on ▁the ▁back , ▁steel - blue ▁on ▁the ▁sides ▁with ▁about ▁ 1 5 ▁sil very ▁bars , ▁and ▁yellow ▁or ▁orange - yellow ▁on ▁the ▁unders ide ; ▁the ▁d ors al ▁fin ▁is ▁m ott led ▁and ▁a ▁small ▁eyes pot ▁may ▁be ▁present ▁near ▁the ▁rear ▁edge . ▁Fem ales ▁tend ▁to ▁be ▁pal er , ▁without ▁bars ▁or ▁the ▁inten se ▁yellow ▁on ▁the ▁bel ly , ▁and ▁their ▁d ors al ▁fin ▁is ▁uniformly ▁col oured . ▁ ▁Ad ult s ▁of ▁the ▁two ▁sub species ▁can ▁be ▁distinguished ▁based ▁on ▁slight ▁morph ological ▁differences . ▁and ▁genom ic ▁Further , ▁eggs ▁of ▁the ▁northern ▁sub species ▁have ▁fil aments ▁( ad hes ive ▁ch or ionic ▁f ibr ils ) ▁that ▁eggs ▁of ▁the ▁southern ▁sub species ▁lack . ▁While ▁the ▁northern ▁sub species ▁depos its ▁eggs ▁in ▁the ▁sand , ▁the ▁southern ▁sub species ▁often ▁depos its ▁eggs ▁inside ▁empty ▁muss el ▁shell s . ▁ ▁The ▁m umm ich og ▁is ▁very ▁similar ▁to ▁the ▁band ed ▁kill if ish , ▁Fund ulus ▁dia phan us , ▁and ▁indeed ▁the ▁two ▁species ▁have ▁been ▁known ▁to ▁inter bre ed . ▁The ▁two ▁species ▁may ▁overlap ▁in ▁their ▁choice ▁of ▁habitat , ▁but ▁in ▁general ▁the