Catfish produced in Nigeria is often grown in tanks or earthen ponds with frequent water exchanges in order to evacuate wastes. However, much of the information on production rates and water exchange are based on anecdotal information and rarely backed up by measurements. Furthermore, only a few farmers record water use because many farmers move fish several times in a single production cycle. Therefore, we decided to test the mode of water exchange to see if there would be any difference in feed consumption or feed conversion so we could better design future trials comparing feeds and comparing different rates of water exchange. Twelve plastic tanks with capacity 1m3 were each stocked with 25 subadult catfish, Clarias gariepinus, averaging 151±2g. Water exchange was designed to use the same total amount of water (500 liters per day), but on three different schedules: treatment 1 was a one-time 500L water exchange per day, treatment 2 was a one-time 1000L single exchange every two days and treatment 3 was a continuous (flow through) slow rate of exchange at a rate of 500L of water per day. The water source was a borehole located on the farm with temperature of ~27.4OC. Water was first pumped into a header tank before discharging into rearing tank during water exchange. All rearing tanks drained their water from the bottom. Fish were fed every afternoon to satiation for 87 days beginning with a feed of 42% crude protein, followed by 33% crude protein feed for a total of 115 days. Treatments 1 and 3 resulted in significantly higher fish growth and better feed conversion than treatment 2. Even though the same amount of water exchange was applied in all treatments, a steady rate or smaller, more frequent exchanges worked better for intensive clarias production. It is recommended to avoid abrupt changes in water quality with Clarias gariepinus even if the replacement water is of better quality for the fish and since the method of water exchange significantly affects some parameters of the fish, it should be noted when reporting trials involving the species.