The larger fish in this tank are Costa Rican blue-eyed cichlids (Amatitlania (Cryptoheros)sajica). All the others are livebearing Goodeids from Mexico; if I remember correctly the principal species are
butterfly goodeids (Ameca splendens) and bluetail goodeids (Ataeniobius toweri). ZSL holds other more endangered Goodeid species off-show.
Goodeids feed by scraping algae off stones, wood and the leaves of higher plants, which they do almost incessantly, which causes these surfaces to appear to be scrubbed (and causes headaches for photographers). The plants are giant Vallisneria.
