The Spanish word 'pescadito' meaning 'small fish' comes from 'pescado' (fish) with the diminutive suffix '-ito'. The word 'pescado' itself derives from the verb 'pescar' (to fish), which comes from Latin 'piscari' (to fish). The Latin 'piscari' was derived from 'piscis' meaning 'fish'. Interestingly, in Spanish, 'pescado' specifically refers to fish that has been caught or fish as food, rather than a living fish in the water (which would be 'pez').

The diminutive suffix '-ito' is a very common and productive suffix in Spanish that adds the meaning of smallness or endearment to the base word. When added to 'pescado', it creates 'pescadito' - literally meaning 'little fish' or 'small fish'.

Some related and commonly used Spanish words include 'pez' (living fish), 'pescar' (to fish), and 'pescador' (fisherman). All these words share the same Latin root 'piscis'. The verb 'pescar' is particularly useful as it's a regular -ar verb that beginning Spanish students learn early on.

English speakers might recognize the connection to words like 'piscine' (relating to fish), 'piscatorial' (relating to fishing), and 'pisces' (the astrological sign of the fish). These English words come from the same Latin root 'piscis'. While these English cognates are somewhat formal or technical, understanding this connection can help remember the Spanish word family related to fish and fishing.