Fish farmers believe that frequent renewal of water from their fish pond automatically helps the growth of their fish but recent research findings state otherwise.
There is no doubt that the physical and chemical qualities of pond water are vital to the success of fish farming as fish’s bodily functions are performed in water. Therefore, water to a great extent determines the success or failure of an aquaculture operation.
Research studies and field trials have clearly shown that frequent pond water renewal or change affects to a great significance the growth performance and nutrient utilization of the catfish.
This is to say that fingerlings/Juveniles constantly disturbed by a frequent pond or rather daily water change, have been observed to exhibit or have lesser growth performance and nutrient utilization than those cultured or raised in ponds in which water is renewed after every 4 to 8 days.
Besides the best growth performance recorded for fingerlings with a water renewal frequency of between 4 to 8 days, the survival rate was also observed to be higher.
Fish farmers are, therefore, advised to renew or change the water between 4 to 8 days for enhanced growth of catfish fingerlings reared in a pond(static water system).
However, care must be taken not to overstock the pond; see our guide on how to stock fish pond. Correct stocking density must be observed to enhance growth and avoid mortality.
It should be noted that the poor growth performance and low survival rate observed infrequently renewed pond water is a result of continuous interference with the dynamics of the pond system on a daily basis as a result of frequent disturbances of the water surface and possibly frequent changes in water quality.
Also, the fish can be highly affected by an increase in stress; this in turn results in less feeding activity and a high value of feed conversion ratio (FCR).
Generally, during the water change, fish tend to spend more time looking for cover and increase swimming and concentration at the four(4) edges of the pond, probably in an attempt to avoid being caught after a recent disturbance in the system.
However, renewing pond water every 4 to 8 days gives the fingerlings enough time to recover and resume active feeding, leading to better-feed conversion and/or utilization.
Undoubtedly, daily renewal of pond water leads to the best water quality but does not necessarily translate into the performance which is basically the main essence of fish culture.
Fish farmers should note that this does not apply in more advanced aquaculture production systems, like Recirculatory Aquaculture System (RAS), race-way, etc, where water is constantly and automatically renewed on daily or hourly bases.
This is because in such system(s) the fish, over time becomes used to the living conditions which are mainly digitally oriented with little or no human interference, and hence minimal stress to fish.