Cultures of larvae require daily maintenance. They are operated most commonly as static water systems, i.e. without a continuous exchange of water, although some hatcheries operate flow-through culture systems (see section 5.1.4.2). Food cell concentrations need to be maintained at levels conducive to efficient feeding activity.
To prevent the accumulation of potentially harmful, metabolites, tanks require complete water changes at regular intervals throughout larval development from the D-stage to the onset of metamorphosis. The frequency with which this is done depends on the number and mean size of larvae being cultured. Water is changed either at 48-hour intervals or 3 times each week: