Ich has and lives in cycles. Disappearance is generally temporary and you must assume that there is still presence. Reason being :
- Free-swimming cells called dinospores are released from a mature cyst and go in search of a host fish.1 Typically these cells can survive seven to eight days without a host, but in lower tank temperatures at around 75-80 degrees, some strains may last up to 30+ days.
- Once a host is found, typically heading for the soft tissue inside the gills first, the dinospores lose their swimming capabilities and become non-motile parasitic trophozoites. At this stage they turn parasitic, as each attaches to the host fish by sending out a filament for feeding.
- After deriving nutrition for 3 days to a week the trophozoites become mature and drop off into the substrate, may remain hidden in the mucus membrane, or sometimes be deeply embedded in the tissue of a host fish, where at this point each forms a type of hard shell covering.
- Inside each encrusted cyst the cells, now called tomonts, reproduce internally by non-sexual division. Upon reaching maturity in about five days, each cyst ruptures and releases hundreds of new free-swimming dinospores to start the cycle all over again, but in much large numbers.
