horrible... they kill more fish then do good imo and ime. your best off haveing someone check them mid-week and doing a "regular" feed. or not feeding them at all.. but as Lupin asked.. depends on the species of fish and imo age. my older predetory fish go weeks w/out food w/out batting a lash if need be. But some of my community fish need to be fed daily or they quickly wither away.