Feed formulation and growth response of pangasius catfish to different protein levels

Abstract:

Feed is the single largest recurring cost in pangasius (Pangasius hypophthalmus) culture, accounting for 62 to 68 percent of the variable cost structure in Mekong Delta farms, yet a sizable share of farmers still use formulations copied from freshwater carp without adjustment for catfish protein demand. This research tested six isocaloric diets with crude protein levels of 24, 28, 32, 36, 40 and 44 percent in pangasius fingerlings of mean initial weight 6.4±0.3 g across a 90-day feeding trial. Fingerlings were stocked at 25 fish per tank in eighteen 300 L fibreglass tanks at the Institutional Aquaculture Unit in Can Tho between April and July 2023. Growth parameters, feed conversion ratio, protein efficiency ratio, specific growth rate and survival were measured. The 40 percent protein diet produced the highest weight gain (70.2 g), best FCR (1.46) and highest protein efficiency (2.83), while the 44 percent treatment gave no additional benefit - a clear inflection point around 40 percent protein. Carcass analysis showed protein retention rising with dietary protein up to 40 percent (21.6% body protein), then plateauing. Nutrient cost analysis returned a feed cost per kilogram of fish gain of VND 18,400 at 40 percent protein against VND 22,200 at 44 percent, making the 40 percent diet also the most economical. The results recommend a 40 percent crude protein formulation as the default for pangasius nursery and grow-out feeds in the Mekong Delta context.