They are normally semi-transparent but may be olive in colour have dark-edges to their scales which creat a distinct, network pattern with a thin black line along the middle of the flanks which becomes more obvious towards the tail..

It is now known to occur at a limited number of sites in the Darling River drainage and an isolated population in the central Lachlan catchment.

Agassiz's perchlet occurs rivers, creeks, ponds and swamps with a preference for slow flowing or still waters where they normally inhabit more sheltered areas where there is overhanging vegetation, beds of aquatic macrophytes, logs, dead branches and boulders where they can hide during the day.

[5] Agassiz's perchlet is threatened by predation by non native fish species which have been introduced into its range such as Gambusia holbrooki and the European perch (Perca fluviatilis).

There has been degradation of its habitat by the removal of vegetation, logs and snags, rapid fluctuations in water levels caused by river regulation have negatively affected their breeding.

The vegetation they shelter in has been lost due to water regulation and through grazing by the introduced common carp (Cyprinus carpio).

[7] The specific name was not explained by Steindachner when he described this species but it almost certainly honours the Swiss-American biologist and geologist Louis Agassiz (1807-1873).