The role of artificial feeding in age-0 channel catfish ponds

Artificial feed is often added to catfish nursery ponds in large quantities to maximize fish growth and final yields at harvest.  However, the mechanisms driving the feeding rate-fish yield relationship are poorly understood.  Theoretically, feeding rate increases fish production by serving as a direct source of nutrition, and indirectly by increasing important natural pond foods (i.e., zooplankton and insects).  However, adding large quantities of nutrient-rich feed to ponds may profoundly decrease harvestable fish yield by deteriorating water quality and stimulating luxuriant growth of harmful algae. 

To develop an effective feeding regimen for age-0 catfish in earthen ponds, we compared the effects of 3%, 1% and 0% body-weight/day feeding rates on fish growth and survival, zooplankton abundance, and water quality.  To model the energetic contribution of artificial and natural pond foods to catfish growth, we used naturally-occurring stable carbon (¹³C) and nitrogen (¹⁵N) isotopes.  We hypothesized that decreasing the feeding rate would decrease fish growth but increase survival by improving water quality.  Surprisingly, we measured equal fish growth among all treatments during the first 5 weeks of culture (P _{trt x time} = 0.304; ANCOVA), suggesting natural pond foods alone provide adequate nutrition during this period in culture.