i.e. changed for coins of smaller denomination, such as obols.
The headword phrase is an approximation (and abridgment) of Aristophanes, Wasps 788-9 (web address 1 below); the Suda has active voice diekerma/tise, but in Aristophanes the verb is middle/passive and may be deponent. See LSJ entry for diakermati/zomai (web address 2). Also, here the tense is aorist, not Aristophanes' imperfect.
The present gloss breaks off incomplete, and the scholia ad loc. do not reveal what element of the phrase is being glossed, or what the glossing word or phrase might have been.
On the idiom 'fish-markets' -- in the Greek simply 'in the fishes' -- see MacDowell 238.